diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index eb7e3a0..fc0a309 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -16,4 +16,4 @@ jobs:
         with:
           java-version: 1.8
       - name: Perform base checks
-        run: ./gradlew demo:assembleDebug firestore:dokka
\ No newline at end of file
+        run: ./gradlew demo:assembleDebug publishToDirectory
\ No newline at end of file
diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..af45bb2
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,16 @@
+Starting from v0.7.0, you can [support development](https://github.com/sponsors/natario1) through the GitHub Sponsors program. 
+Companies can share a tiny part of their revenue and get private support hours in return. Thanks!
+
+## v0.7.0
+
+- New: Upgrade to Kotlin 1.4, Firestore 21.6.0 ([#12][12])
+- Breaking change: `FirestoreParcelers.add` is now `registerParceler` or `FirestoreParceler.register` ([#12][12])
+- Breaking change: `FirestoreDocument.CacheState` is now `FirestoreCacheState` ([#12][12])
+- Breaking change: parcelers moved to `com.otaliastudios.firestore.parcel.*` package ([#12][12])
+- Fix: do not crash exception when metadata is not present ([#12][12])
+
+<https://github.com/natario1/Egloo/compare/v0.6.0...v0.7.0>
+
+[natario1]: https://github.com/natario1
+
+[12]: https://github.com/natario1/Firestore/pull/12
diff --git a/README.md b/README.md
index 86b89d0..81a18ab 100644
--- a/README.md
+++ b/README.md
@@ -11,8 +11,8 @@
 The lightweight, efficient wrapper for Firestore model data, written in Kotlin, with data-binding and Parcelable support.
 
 ```groovy
-implementation 'com.otaliastudios:firestore:0.6.0'
-kapt 'com.otaliastudios:firestore-compiler:0.6.0'
+implementation 'com.otaliastudios:firestore:0.7.0'
+kapt 'com.otaliastudios:firestore-compiler:0.7.0'
 ```
 
 - Efficient and lightweight
@@ -185,15 +185,15 @@ a parceler using `FirestoreDocument.registerParceler()`:
 class App : Application() {
 
     override fun onCreate() {
-        FirestoreDocument.registerParceler(GeoPoint::class, GeoPointParceler())
-        FirestoreDocument.registerParceler(Whatever::class, WhateverParceler())
+        registerParceler(GeoPointParceler)
+        registerParceler(WhateverParceler)
     }
     
-    class GeoPointParceler : FirestoreDocument.Parceler<GeoPoint>() {
+    object GeoPointParceler : FirestoreDocument.Parceler<GeoPoint>() {
         // ...
     }
     
-    class WhateverParceler : FirestoreDocument.Parceler<Whatever>() {
+    object WhateverParceler : FirestoreDocument.Parceler<Whatever>() {
         // ...
     }
 }
diff --git a/build.gradle.kts b/build.gradle.kts
index 342f69e..9ca7688 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -5,7 +5,7 @@
 buildscript {
 
     extra["libDescription"] = "The efficient wrapper for Firestore model data."
-    extra["libVersion"] = "0.6.0"
+    extra["libVersion"] = "0.7.0"
     extra["libGroup"] = "com.otaliastudios"
     extra["githubUrl"] = "https://github.com/natario1/Firestore"
     extra["githubGit"] = "https://github.com/natario1/Firestore.git"
@@ -13,7 +13,6 @@ buildscript {
     extra["minSdkVersion"] = 16
     extra["compileSdkVersion"] = 29
     extra["targetSdkVersion"] = 29
-    extra["kotlinVersion"] = "1.3.61"
 
     repositories {
         google()
@@ -22,10 +21,9 @@ buildscript {
     }
 
     dependencies {
-        val kotlinVersion = property("kotlinVersion") as String
-        classpath("com.android.tools.build:gradle:3.6.1")
-        classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlinVersion")
-        classpath("com.otaliastudios.tools:publisher:0.1.5")
+        classpath("com.android.tools.build:gradle:4.0.1")
+        classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:1.4.0")
+        classpath("com.otaliastudios.tools:publisher:0.3.3")
     }
 }
 
diff --git a/buildSrc/.gitignore b/buildSrc/.gitignore
deleted file mode 100644
index 796b96d..0000000
--- a/buildSrc/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-/build
diff --git a/buildSrc/build.gradle.kts b/buildSrc/build.gradle.kts
deleted file mode 100644
index 55be88e..0000000
--- a/buildSrc/build.gradle.kts
+++ /dev/null
@@ -1,15 +0,0 @@
-/*
- * Copyright (c) 2020 Otalia Studios. Author: Mattia Iavarone.
- */
-
-plugins {
-    `kotlin-dsl`
-}
-
-repositories {
-    // Nothing yet
-}
-
-dependencies {
-    // Nothing yet
-}
\ No newline at end of file
diff --git a/compiler/build.gradle.kts b/compiler/build.gradle.kts
index 27bfb9c..672f227 100644
--- a/compiler/build.gradle.kts
+++ b/compiler/build.gradle.kts
@@ -2,12 +2,12 @@
  * Copyright (c) 2018 Otalia Studios. Author: Mattia Iavarone.
  */
 
-import com.otaliastudios.tools.publisher.PublisherExtension.License
-import com.otaliastudios.tools.publisher.PublisherExtension.Release
+import com.otaliastudios.tools.publisher.common.License
+import com.otaliastudios.tools.publisher.common.Release
 
 plugins {
     id("kotlin")
-    id("maven-publisher-bintray")
+    id("com.otaliastudios.tools.publisher")
 }
 
 java {
@@ -16,17 +16,12 @@ java {
 }
 
 dependencies {
-    val kotlinVersion = property("kotlinVersion") as String
-    api("org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlinVersion")
     api("com.squareup:kotlinpoet:1.5.0")
     api("com.squareup:kotlinpoet-metadata:1.5.0")
     api("com.squareup:kotlinpoet-metadata-specs:1.5.0")
 }
 
 publisher {
-    auth.user = "BINTRAY_USER"
-    auth.key = "BINTRAY_KEY"
-    auth.repo = "BINTRAY_REPO"
     project.artifact = "firestore-compiler"
     project.description = property("libDescription") as String
     project.group = property("libGroup") as String
@@ -36,4 +31,12 @@ publisher {
     release.version = property("libVersion") as String
     release.setSources(Release.SOURCES_AUTO)
     release.setDocs(Release.DOCS_AUTO)
+    bintray {
+        auth.user = "BINTRAY_USER"
+        auth.key = "BINTRAY_KEY"
+        auth.repo = "BINTRAY_REPO"
+    }
+    directory {
+        directory = "../build/maven"
+    }
 }
diff --git a/demo/build.gradle.kts b/demo/build.gradle.kts
index 3cdff56..b2c7e89 100644
--- a/demo/build.gradle.kts
+++ b/demo/build.gradle.kts
@@ -34,10 +34,7 @@ dependencies {
 
     implementation(project(":firestore"))
     kapt(project(":compiler"))
-
-    val kotlin = rootProject.extra["kotlinVersion"]
-    implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin")
-    implementation("androidx.appcompat:appcompat:1.1.0")
-    implementation("androidx.core:core-ktx:1.2.0")
-    implementation("androidx.constraintlayout:constraintlayout:1.1.3")
+    implementation("androidx.appcompat:appcompat:1.2.0")
+    implementation("androidx.core:core-ktx:1.3.1")
+    implementation("androidx.constraintlayout:constraintlayout:2.0.1")
 }
diff --git a/firestore/build.gradle.kts b/firestore/build.gradle.kts
index 50e35b8..b061986 100644
--- a/firestore/build.gradle.kts
+++ b/firestore/build.gradle.kts
@@ -2,13 +2,13 @@
  * Copyright (c) 2018 Otalia Studios. Author: Mattia Iavarone.
  */
 
-import com.otaliastudios.tools.publisher.PublisherExtension.License
-import com.otaliastudios.tools.publisher.PublisherExtension.Release
+import com.otaliastudios.tools.publisher.common.License
+import com.otaliastudios.tools.publisher.common.Release
 
 plugins {
     id("com.android.library")
     id("kotlin-android")
-    id("maven-publisher-bintray")
+    id("com.otaliastudios.tools.publisher")
 }
 
 android {
@@ -19,11 +19,13 @@ android {
         versionName = property("libVersion") as String
     }
 
-    dataBinding.isEnabled = true
+    buildFeatures {
+        dataBinding = true
+    }
 
     sourceSets {
-        get("main").java.srcDirs("src/main/kotlin")
-        get("test").java.srcDirs("src/test/kotlin")
+        getByName("main").java.srcDirs("src/main/kotlin")
+        getByName("test").java.srcDirs("src/test/kotlin")
     }
 
     compileOptions {
@@ -32,21 +34,21 @@ android {
     }
 
     buildTypes {
-        get("release").consumerProguardFile("proguard-rules.pro")
+        getByName("release").consumerProguardFile("proguard-rules.pro")
+    }
+
+    kotlinOptions {
+        // Until the explicitApi() works in the Kotlin block...
+        // https://youtrack.jetbrains.com/issue/KT-37652
+        freeCompilerArgs += listOf("-Xexplicit-api=strict")
     }
 }
 
 dependencies {
-    val kotlinVersion = property("kotlinVersion")
-    api("org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlinVersion")
-    api("com.google.firebase:firebase-firestore:21.4.1")
-    api("com.jakewharton.timber:timber:4.7.1")
+    api("com.google.firebase:firebase-firestore-ktx:21.6.0")
 }
 
 publisher {
-    auth.user = "BINTRAY_USER"
-    auth.key = "BINTRAY_KEY"
-    auth.repo = "BINTRAY_REPO"
     project.artifact = "firestore"
     project.description = property("libDescription") as String
     project.group = property("libGroup") as String
@@ -55,4 +57,12 @@ publisher {
     project.addLicense(License.APACHE_2_0)
     release.setSources(Release.SOURCES_AUTO)
     release.setDocs(Release.DOCS_AUTO)
+    bintray {
+        auth.user = "BINTRAY_USER"
+        auth.key = "BINTRAY_KEY"
+        auth.repo = "BINTRAY_REPO"
+    }
+    directory {
+        directory = "../build/maven"
+    }
 }
\ No newline at end of file
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/Annotations.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/Annotations.kt
deleted file mode 100644
index 96baa5d..0000000
--- a/firestore/src/main/kotlin/com/otaliastudios/firestore/Annotations.kt
+++ /dev/null
@@ -1,24 +0,0 @@
-/*
- * Copyright (c) 2018 Otalia Studios. Author: Mattia Iavarone.
- */
-
-package com.otaliastudios.firestore
-
-import androidx.annotation.Keep
-
-@Keep
-@Target(AnnotationTarget.CLASS)
-@Retention(AnnotationRetention.RUNTIME)
-annotation class FirestoreClass
-
-@Keep
-public interface FirestoreMetadata {
-    fun <T> create(key: String): T?
-    fun isNullable(key: String): Boolean
-    fun getBindableResource(key: String): Int?
-    fun <T> createInnerType(): T?
-
-    companion object {
-        const val SUFFIX = "MetadataImpl"
-    }
-}
\ No newline at end of file
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/Extensions.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/Extensions.kt
deleted file mode 100644
index 778b205..0000000
--- a/firestore/src/main/kotlin/com/otaliastudios/firestore/Extensions.kt
+++ /dev/null
@@ -1,81 +0,0 @@
-package com.otaliastudios.firestore
-
-import com.google.android.gms.tasks.Task
-import com.google.firebase.firestore.DocumentSnapshot
-import com.otaliastudios.firestore.batch.FirestoreBatchWrite
-import com.otaliastudios.firestore.batch.FirestoreBatchWriter
-import kotlin.reflect.KClass
-
-@Suppress("UNCHECKED_CAST", "RedundantVisibilityModifier")
-public fun <T: FirestoreDocument> DocumentSnapshot.toFirestoreDocument(type: KClass<T>, cache: Boolean = true): T {
-    var needsCacheState = false
-    val result = if (cache) {
-        val cached = FirestoreDocument.CACHE.get(reference.id) as? T
-        if (cached == null) {
-            FirestoreLogger.i { "Id ${reference.id} asked for cache. Cache miss." }
-            val new = type.java.newInstance()
-            new.clearDirt() // Clear dirtyness from init().
-            FirestoreDocument.CACHE.put(reference.id, new)
-            new.cacheState = FirestoreDocument.CacheState.FRESH
-            new
-        } else {
-            if (metadata.isFromCache) {
-                FirestoreLogger.i { "Id ${reference.id} asked for cache. Was found. Using CACHED_EQUAL because metadata.isFromCache." }
-                cached.cacheState = FirestoreDocument.CacheState.CACHED_EQUAL
-            } else {
-                FirestoreLogger.i { "Id ${reference.id} asked for cache. Was found. We'll see if something changed." }
-                needsCacheState = true
-                /* val map = mutableMapOf<String, Any?>()
-                cached.collectAllValues(map, "")
-                cached.cacheState = if (map.any { get(it.key) != it.value }) {
-                    FirestoreLogger.v("Id ${reference.id} asked for cache. Was found. Using CACHED_CHANGED because some values were different.")
-                    FirestoreDocument.CacheState.CACHED_CHANGED
-                } else {
-                    FirestoreLogger.v("Id ${reference.id} asked for cache. Was found. Using CACHED_EQUAL because everything matches.")
-                    FirestoreDocument.CacheState.CACHED_EQUAL
-                } */
-            }
-            cached
-        }
-    } else {
-        FirestoreLogger.i { "Id ${reference.id} created with no cache." }
-        val new = type.java.newInstance()
-        new.clearDirt() // Clear dirtyness from init().
-        FirestoreDocument.CACHE.put(reference.id, new)
-        new.cacheState = FirestoreDocument.CacheState.FRESH
-        new
-    }
-    result.id = reference.id
-    result.collection = reference.parent.path
-    val changed = result.mergeValues(data!!, needsCacheState, reference.id)
-    if (needsCacheState) {
-        result.cacheState = if (changed) {
-            FirestoreLogger.v { "Id ${reference.id} Setting cache state to CACHED_CHANGED." }
-            FirestoreDocument.CacheState.CACHED_CHANGED
-        } else {
-            FirestoreLogger.v { "Id ${reference.id} Setting cache state to CACHED_EQUAL." }
-            FirestoreDocument.CacheState.CACHED_EQUAL
-        }
-    }
-    return result
-}
-
-@Suppress("RedundantVisibilityModifier")
-public inline fun <reified T: FirestoreDocument> DocumentSnapshot.toFirestoreDocument(cache: Boolean = true): T {
-    return toFirestoreDocument(T::class, cache)
-}
-
-public fun <T: Any> firestoreListOf(vararg elements: T): FirestoreList<T> {
-    return FirestoreList(elements.asList())
-}
-
-public fun <T> firestoreMapOf(vararg pairs: Pair<String, T>): FirestoreMap<T> {
-    return FirestoreMap(pairs.toMap())
-}
-
-public fun batchWrite(updates: FirestoreBatchWriter.() -> Unit): Task<Unit> {
-    return FirestoreBatchWrite().run {
-        perform(updates)
-        commit()
-    }
-}
\ No newline at end of file
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreClass.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreClass.kt
new file mode 100644
index 0000000..0bb134e
--- /dev/null
+++ b/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreClass.kt
@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2018 Otalia Studios. Author: Mattia Iavarone.
+ */
+
+package com.otaliastudios.firestore
+
+import androidx.annotation.Keep
+
+/**
+ * Identifies [FirestoreDocument], [FirestoreMap]s and [FirestoreList]s
+ * so that they can be processed by the annotation processor.
+ */
+@Keep
+@Target(AnnotationTarget.CLASS)
+@Retention(AnnotationRetention.RUNTIME)
+public annotation class FirestoreClass
+// Keep in sync with compiler!
\ No newline at end of file
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreDocument.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreDocument.kt
index cebaa28..4d1db36 100755
--- a/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreDocument.kt
+++ b/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreDocument.kt
@@ -4,30 +4,30 @@
 
 package com.otaliastudios.firestore
 
-import android.annotation.SuppressLint
 import android.os.Bundle
-import android.util.LruCache
 import androidx.annotation.Keep
-import com.google.android.gms.common.api.Batch
 import com.google.android.gms.tasks.Task
 import com.google.android.gms.tasks.Tasks
 import com.google.firebase.Timestamp
 import com.google.firebase.firestore.*
+import com.otaliastudios.firestore.parcel.DocumentReferenceParceler
+import com.otaliastudios.firestore.parcel.FieldValueParceler
+import com.otaliastudios.firestore.parcel.TimestampParceler
 import kotlin.reflect.KClass
 
 /**
  * The base document class.
  */
 @Keep
-abstract class FirestoreDocument(
-        @get:Exclude var collection: String? = null,
-        @get:Exclude var id: String? = null,
+public abstract class FirestoreDocument(
+        @get:Exclude public var collection: String? = null,
+        @get:Exclude public var id: String? = null,
         source: Map<String, Any?>? = null
 ) : FirestoreMap<Any?>(source = source) {
 
     @Suppress("MemberVisibilityCanBePrivate", "RedundantModalityModifier")
     @Exclude
-    final fun isNew(): Boolean {
+    public final fun isNew(): Boolean {
         return createdAt == null
     }
 
@@ -40,39 +40,42 @@ abstract class FirestoreDocument(
     }
 
     @Exclude
-    fun getReference(): DocumentReference {
+    public fun getReference(): DocumentReference {
         if (id == null) throw IllegalStateException("Cant return reference for unsaved data.")
         return requireReference()
     }
 
     @get:Keep @set:Keep
-    var createdAt: Timestamp? by this
+    public var createdAt: Timestamp? by this
 
     @get:Keep @set:Keep
-    var updatedAt: Timestamp? by this
+    public var updatedAt: Timestamp? by this
 
-    internal var cacheState: CacheState = CacheState.FRESH
+    internal var cacheState: FirestoreCacheState = FirestoreCacheState.FRESH
 
+    @Suppress("unused")
     @Exclude
-    fun getCacheState() = cacheState
+    public fun getCacheState(): FirestoreCacheState = cacheState
 
+    @Suppress("unused")
     @Exclude
-    fun delete(): Task<Unit> {
+    public fun delete(): Task<Unit> {
         @Suppress("UNCHECKED_CAST")
         return getReference().delete() as Task<Unit>
     }
 
     @Exclude
-    internal fun delete(batch: WriteBatch): BatchOp {
+    internal fun delete(batch: WriteBatch): FirestoreBatchOp {
         batch.delete(getReference())
-        return object: BatchOp {
+        return object: FirestoreBatchOp {
             override fun notifyFailure() {}
             override fun notifySuccess() {}
         }
     }
 
+    @Suppress("unused")
     @Exclude
-    fun <T: FirestoreDocument> save(): Task<T> {
+    public fun <T: FirestoreDocument> save(): Task<T> {
         return when {
             isNew() -> create()
             else -> update()
@@ -80,7 +83,7 @@ abstract class FirestoreDocument(
     }
 
     @Exclude
-    internal fun save(batch: WriteBatch): BatchOp {
+    internal fun save(batch: WriteBatch): FirestoreBatchOp {
         return when {
             isNew() -> create(batch)
             else -> update(batch)
@@ -112,9 +115,9 @@ abstract class FirestoreDocument(
         // Add to cache NOW, then eventually revert.
         // This is because when reference.set() succeeds, any query listener is notified
         // before our onSuccessTask() is called. So a new item is created.
-        FirestoreDocument.CACHE.put(reference.id, this)
+        FirestoreCache[reference.id] = this
         return reference.set(map).addOnFailureListener {
-            FirestoreDocument.CACHE.remove(reference.id)
+            FirestoreCache.remove(reference.id)
         }.onSuccessTask {
             id = reference.id
             createdAt = Timestamp.now()
@@ -125,13 +128,13 @@ abstract class FirestoreDocument(
         }
     }
 
-    private fun update(batch: WriteBatch): BatchOp {
+    private fun update(batch: WriteBatch): FirestoreBatchOp {
         if (isNew()) throw IllegalStateException("Can not update a new object. Please call create().")
         val map = mutableMapOf<String, Any?>()
         flattenValues(map, prefix = "", dirtyOnly = true)
         map["updatedAt"] = FieldValue.serverTimestamp()
         batch.update(getReference(), map)
-        return object: BatchOp {
+        return object: FirestoreBatchOp {
             override fun notifyFailure() {}
             override fun notifySuccess() {
                 updatedAt = Timestamp.now()
@@ -140,17 +143,17 @@ abstract class FirestoreDocument(
         }
     }
 
-    private fun create(batch: WriteBatch): BatchOp {
+    private fun create(batch: WriteBatch): FirestoreBatchOp {
         if (!isNew()) throw IllegalStateException("Can not create an existing object.")
         val reference = requireReference()
         val map = collectValues(dirtyOnly = false).toMutableMap()
         map["createdAt"] = FieldValue.serverTimestamp()
         map["updatedAt"] = FieldValue.serverTimestamp()
         batch.set(reference, map)
-        FirestoreDocument.CACHE.put(reference.id, this)
-        return object: BatchOp {
+        FirestoreCache[reference.id] = this
+        return object: FirestoreBatchOp {
             override fun notifyFailure() {
-                FirestoreDocument.CACHE.remove(reference.id)
+                FirestoreCache.remove(reference.id)
             }
 
             override fun notifySuccess() {
@@ -162,13 +165,9 @@ abstract class FirestoreDocument(
         }
     }
 
-    internal interface BatchOp {
-        fun notifySuccess()
-        fun notifyFailure()
-    }
-
+    @Suppress("unused")
     @Exclude
-    fun <T: FirestoreDocument> trySave(vararg updates: Pair<String, Any?>): Task<T> {
+    public fun <T: FirestoreDocument> trySave(vararg updates: Pair<String, Any?>): Task<T> {
         if (isNew()) throw IllegalStateException("Can not trySave a new object. Please call save() first.")
         val reference = requireReference()
         val values = updates.toMap().toMutableMap()
@@ -193,54 +192,6 @@ abstract class FirestoreDocument(
         }
     }
 
-    override fun equals(other: Any?): Boolean {
-        if (this === other) return true
-        return other is FirestoreDocument &&
-                other.id == this.id &&
-                other.collection == this.collection &&
-                super.equals(other)
-    }
-
-    companion object {
-
-        @SuppressLint("StaticFieldLeak")
-        internal val FIRESTORE = FirebaseFirestore.getInstance().apply {
-            firestoreSettings = FirebaseFirestoreSettings.Builder()
-                .setTimestampsInSnapshotsEnabled(true)
-                .build()
-        }
-
-        internal val CACHE = LruCache<String, FirestoreDocument>(100)
-
-        private val METADATA_PROVIDERS = mutableMapOf<String, FirestoreMetadata>()
-
-        internal fun metadataProvider(klass: KClass<*>): FirestoreMetadata {
-            val name = klass.java.name
-            if (!METADATA_PROVIDERS.containsKey(name)) {
-                val classPackage = klass.java.`package`!!.name
-                val className = klass.java.simpleName
-                val metadata = Class.forName("$classPackage.$className${FirestoreMetadata.SUFFIX}")
-                METADATA_PROVIDERS[name] = metadata.newInstance() as FirestoreMetadata
-            }
-            return METADATA_PROVIDERS[name] as FirestoreMetadata
-        }
-
-        init {
-            FirestoreParcelers.add(DocumentReference::class, DocumentReferenceParceler)
-            FirestoreParcelers.add(Timestamp::class, TimestampParceler)
-            FirestoreParcelers.add(FieldValue::class, FieldValueParceler)
-        }
-
-        fun <T: FirestoreDocument> getCached(id: String, type: KClass<T>): T? {
-            @Suppress("UNCHECKED_CAST")
-            return CACHE.get(id) as? T
-        }
-
-        inline fun <reified T: FirestoreDocument> getCached(id: String): T? {
-            return getCached(id, T::class)
-        }
-    }
-
     override fun onWriteToBundle(bundle: Bundle) {
         super.onWriteToBundle(bundle)
         bundle.putString("id", id)
@@ -253,7 +204,22 @@ abstract class FirestoreDocument(
         collection = bundle.getString("collection", null)
     }
 
-    enum class CacheState {
-        FRESH, CACHED_EQUAL, CACHED_CHANGED
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        return other is FirestoreDocument &&
+                other.id == this.id &&
+                other.collection == this.collection &&
+                super.equals(other)
+    }
+
+    public companion object {
+        @Deprecated(message = "Use FirestoreCache directly.", replaceWith = ReplaceWith("FirestoreCache.get"))
+        public fun <T: FirestoreDocument> getCached(id: String, type: KClass<T>): T?
+                = FirestoreCache.get(id, type)
+
+        @Suppress("unused")
+        @Deprecated(message = "Use FirestoreCache directly.", replaceWith = ReplaceWith("FirestoreCache.get"))
+        public inline fun <reified T: FirestoreDocument> getCached(id: String): T?
+                = FirestoreCache[id]
     }
 }
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreList.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreList.kt
index eeeb1c2..a005fe4 100644
--- a/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreList.kt
+++ b/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreList.kt
@@ -9,24 +9,34 @@ import android.os.Parcel
 import android.os.Parcelable
 import androidx.annotation.Keep
 import com.google.firebase.firestore.Exclude
+import com.otaliastudios.firestore.parcel.readValue
+import com.otaliastudios.firestore.parcel.writeValue
 
 /**
- * A list implementation. Delegates to a mutable list.
- *
- * The point of list is dirtyness.
+ * Creates a [FirestoreList] for the given values.
+ */
+@Suppress("unused")
+public fun <T: Any> firestoreListOf(vararg values: T): FirestoreList<T> {
+    return FirestoreList(values.asList())
+}
+
+/**
+ * A [FirestoreList] can be used to represent firestore lists.
+ * Implements list methods by delegates to a mutable list under the hood.
  *
- * When an item is inserted, removed, or when a inner FirestoreMap/List is changed,
- * this list should be marked as dirty.
+ * Whenever an item is inserted, removed, or when a inner Map/List is changed,
+ * this list will be marked as dirty.
  */
 @Keep
-open class FirestoreList<T: Any> @JvmOverloads constructor(
+public open class FirestoreList<T: Any> @JvmOverloads constructor(
         source: List<T>? = null
-) : /* ObservableList<T>, MutableList<T> by data, */Iterable<T>, Parcelable {
+) : Iterable<T>, Parcelable {
 
+    private val log = FirestoreLogger("FirestoreList")
     private val data: MutableList<T> = mutableListOf()
 
     @get:Exclude
-    val size get() = data.size
+    public val size: Int get() = data.size
 
     init {
         if (source != null) {
@@ -94,29 +104,25 @@ open class FirestoreList<T: Any> @JvmOverloads constructor(
     }
 
     private fun <K> createFirestoreMap(): FirestoreMap<K> {
-        val map = try { onCreateFirestoreMap<K>() } catch (e: Exception) {
-            FirestoreMap<K>()
-        }
+        val map = onCreateFirestoreMap<K>()
         map.clearDirt()
         return map
     }
 
     private fun <K: Any> createFirestoreList(): FirestoreList<K> {
-        val list = try { onCreateFirestoreList<K>() } catch (e: Exception) {
-            FirestoreList<K>()
-        }
+        val list = onCreateFirestoreList<K>()
         list.clearDirt()
         return list
     }
 
     protected open fun <K> onCreateFirestoreMap(): FirestoreMap<K> {
-        val provider = FirestoreDocument.metadataProvider(this::class)
-        return provider.createInnerType<FirestoreMap<K>>() ?: FirestoreMap()
+        val metadata = this::class.metadata
+        return metadata?.createInnerType<FirestoreMap<K>>() ?: FirestoreMap()
     }
 
     protected open fun <K: Any> onCreateFirestoreList(): FirestoreList<K> {
-        val provider = FirestoreDocument.metadataProvider(this::class)
-        return provider.createInnerType<FirestoreList<K>>() ?: FirestoreList()
+        val metadata = this::class.metadata
+        return metadata?.createInnerType<FirestoreList<K>>() ?: FirestoreList()
     }
 
     @Suppress("UNCHECKED_CAST")
@@ -167,43 +173,45 @@ open class FirestoreList<T: Any> @JvmOverloads constructor(
 
     // Parcelable stuff.
 
-    override fun describeContents() = 0
+    override fun describeContents(): Int = 0
 
     override fun writeToParcel(parcel: Parcel, flags: Int) {
         val hashcode = hashCode()
         parcel.writeInt(hashcode)
 
         // Write class name
-        FirestoreLogger.i { "List $hashcode: writing class ${this::class.java.name}" }
+        log.i { "List $hashcode: writing class ${this::class.java.name}" }
         parcel.writeString(this::class.java.name)
 
         // Write size and dirtiness
-        FirestoreLogger.v { "List $hashcode: writing dirty $isDirty and size $size" }
+        log.v { "List $hashcode: writing dirty $isDirty and size $size" }
         parcel.writeInt(if (isDirty) 1 else 0)
         parcel.writeInt(size)
 
         // Write actual data
         for (value in data) {
-            FirestoreLogger.v { "List $hashcode: writing value $value" }
-            FirestoreParcelers.write(parcel, value, hashcode.toString())
+            log.v { "List $hashcode: writing value $value" }
+            parcel.writeValue(value, hashcode.toString())
         }
 
         // Extra bundle
         val bundle = Bundle()
         onWriteToBundle(bundle)
-        FirestoreLogger.v { "List $hashcode: writing extra bundle. Size is ${bundle.size()}" }
+        log.v { "List $hashcode: writing extra bundle. Size is ${bundle.size()}" }
         parcel.writeBundle(bundle)
     }
 
-    companion object {
+    public companion object {
+
+        private val LOG = FirestoreLogger("FirestoreList")
 
         @Suppress("unused")
         @JvmField
-        public val CREATOR = object : Parcelable.ClassLoaderCreator<FirestoreList<Any>> {
+        public val CREATOR: Parcelable.Creator<FirestoreList<Any>> = object : Parcelable.ClassLoaderCreator<FirestoreList<Any>> {
 
             override fun createFromParcel(source: Parcel): FirestoreList<Any> {
                 // This should never be called by the framework.
-                FirestoreLogger.e { "List: received call to createFromParcel without classLoader." }
+                LOG.e { "List: received call to createFromParcel without classLoader." }
                 return createFromParcel(source, FirestoreList::class.java.classLoader!!)
             }
 
@@ -211,25 +219,25 @@ open class FirestoreList<T: Any> @JvmOverloads constructor(
                 val hashcode = parcel.readInt()
                 // Read class name
                 val klass = Class.forName(parcel.readString()!!)
-                FirestoreLogger.i { "List $hashcode: read class ${klass.simpleName}" }
+                LOG.i { "List $hashcode: read class ${klass.simpleName}" }
                 @Suppress("UNCHECKED_CAST")
                 val dataList = klass.newInstance() as FirestoreList<Any>
 
                 // Read dirtyness and size
                 dataList.isDirty = parcel.readInt() == 1
                 val count = parcel.readInt()
-                FirestoreLogger.v { "List $hashcode: read dirtyness ${dataList.isDirty} and size $count" }
+                LOG.v { "List $hashcode: read dirtyness ${dataList.isDirty} and size $count" }
 
                 // Read actual data
                 repeat(count) {
-                    FirestoreLogger.v { "List $hashcode: reading value..." }
-                    dataList.data.add(FirestoreParcelers.read(parcel, loader, hashcode.toString())!!)
+                    LOG.v { "List $hashcode: reading value..." }
+                    dataList.data.add(parcel.readValue(loader, hashcode.toString())!!)
                 }
 
                 // Extra bundle
-                FirestoreLogger.v { "List $hashcode: reading extra bundle." }
+                LOG.v { "List $hashcode: reading extra bundle." }
                 val bundle = parcel.readBundle(loader)!!
-                FirestoreLogger.v { "List $hashcode: read extra bundle, size ${bundle.size()}" }
+                LOG.v { "List $hashcode: read extra bundle, size ${bundle.size()}" }
                 dataList.onReadFromBundle(bundle)
                 return dataList
             }
@@ -246,24 +254,24 @@ open class FirestoreList<T: Any> @JvmOverloads constructor(
 
     // Dirtyness stuff.
 
-    fun add(element: T): Boolean {
+    public fun add(element: T): Boolean {
         data.add(element)
         isDirty = true
         return true
     }
 
-    fun add(index: Int, element: T) {
+    public fun add(index: Int, element: T) {
         data.add(index, element)
         isDirty = true
     }
 
-    fun remove(element: T): Boolean {
+    public fun remove(element: T): Boolean {
         val result = data.remove(element)
         isDirty = true
         return result
     }
 
-    operator fun set(index: Int, element: T): T {
+    public operator fun set(index: Int, element: T): T {
         val value = data.set(index, element)
         isDirty = true
         return value
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreLogger.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreLogger.kt
index 252fc56..5ad2d0c 100644
--- a/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreLogger.kt
+++ b/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreLogger.kt
@@ -1,50 +1,58 @@
+@file:Suppress("unused")
+
 package com.otaliastudios.firestore
 
 import android.util.Log
-import timber.log.Timber
 
-object FirestoreLogger {
+/**
+ * Lazy logger used across the library.
+ * Use [setLevel] to configure the verbosity.
+ */
+public class FirestoreLogger internal constructor(private val tag: String) {
 
-    const val VERBOSE = Log.VERBOSE
-    const val INFO = Log.INFO
-    const val WARN = Log.WARN
-    const val ERROR = Log.ERROR
+    public companion object {
+        public const val VERBOSE: Int = Log.VERBOSE
+        public const val INFO: Int = Log.INFO
+        public const val WARN: Int = Log.WARN
+        public const val ERROR: Int = Log.ERROR
 
-    private var level = ERROR
+        private var level = WARN
 
-    fun setLevel(level: Int) {
-        this.level = level
+        @JvmStatic
+        public fun setLevel(level: Int) {
+            this.level = level
+        }
     }
 
     internal fun w(message: () -> String) {
-        if (level <= WARN) Timber.w(message())
+        if (level <= WARN) Log.w(tag, message())
     }
 
     internal fun w(throwable: Throwable, message: () -> String) {
-        if (level <= WARN) Timber.w(throwable, message())
+        if (level <= WARN) Log.w(tag, message(), throwable)
     }
 
     internal fun e(message: () -> String) {
-        if (level <= ERROR) Timber.e(message())
+        if (level <= ERROR) Log.e(tag, message())
     }
 
     internal fun e(throwable: Throwable, message: () -> String) {
-        if (level <= ERROR) Timber.e(throwable, message())
+        if (level <= ERROR) Log.e(tag, message(), throwable)
     }
 
     internal fun i(message: () -> String) {
-        if (level <= INFO) Timber.i(message())
+        if (level <= INFO) Log.i(tag, message())
     }
 
-    internal fun i(throwable: Throwable, message: String) {
-        if (level <= INFO) Timber.i(throwable, message)
+    internal fun i(throwable: Throwable, message: () -> String) {
+        if (level <= INFO) Log.i(tag, message(), throwable)
     }
 
     internal fun v(message: () -> String) {
-        if (level <= VERBOSE) Timber.v(message())
+        if (level <= VERBOSE) Log.v(tag, message())
     }
 
     internal fun v(throwable: Throwable, message: () -> String) {
-        if (level <= VERBOSE) Timber.v(throwable, message())
+        if (level <= VERBOSE) Log.v(tag, message(), throwable)
     }
 }
\ No newline at end of file
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreMap.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreMap.kt
index d8f267d..a9e8280 100644
--- a/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreMap.kt
+++ b/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreMap.kt
@@ -10,26 +10,34 @@ import android.os.Parcelable
 import androidx.annotation.Keep
 import androidx.databinding.BaseObservable
 import com.google.firebase.firestore.Exclude
-import java.util.LinkedHashMap
+import com.otaliastudios.firestore.parcel.readValue
+import com.otaliastudios.firestore.parcel.writeValue
 import kotlin.reflect.KProperty
 
 /**
- * A map implementation. Delegates to a mutable map.
- * Introduce dirtyness checking for childrens.
+ * Creates a [FirestoreMap] for the given key-value pairs.
+ */
+@Suppress("unused")
+public fun <T> firestoreMapOf(vararg pairs: Pair<String, T>): FirestoreMap<T> {
+    return FirestoreMap(pairs.toMap())
+}
+
+/**
+ * A [FirestoreMap] can be used to represent firestore JSON-like structures.
+ * Implements map methods by delegating to a mutable map under the hood.
  */
 @Keep
-open class FirestoreMap<T>(
-        source: Map<String, T>? = null
-) : BaseObservable(), /*MutableMap<String, T> by data,*/ Parcelable {
+public open class FirestoreMap<T>(source: Map<String, T>? = null) : BaseObservable(), Parcelable {
 
+    private val log = FirestoreLogger("FirestoreMap")
     private val data: MutableMap<String, T> = mutableMapOf()
     private val dirty: MutableSet<String> = mutableSetOf()
 
     @get:Exclude
-    val keys get() = data.keys
+    public val keys: Set<String> get() = data.keys
 
     @get:Exclude
-    val size get() = data.size
+    public val size: Int get() = data.size
 
     init {
         if (source != null) {
@@ -82,38 +90,34 @@ open class FirestoreMap<T>(
 
 
     private fun <K> createFirestoreMap(key: String): FirestoreMap<K> {
-        val map = try { onCreateFirestoreMap<K>(key) } catch (e: Exception) {
-            FirestoreMap<K>()
-        }
+        val map = onCreateFirestoreMap<K>(key)
         map.clearDirt()
         return map
     }
 
     private fun <K: Any> createFirestoreList(key: String): FirestoreList<K> {
-        val list = try { onCreateFirestoreList<K>(key) } catch (e: Exception) {
-            FirestoreList<K>()
-        }
+        val list = onCreateFirestoreList<K>(key)
         list.clearDirt()
         return list
     }
 
     protected open fun <K> onCreateFirestoreMap(key: String): FirestoreMap<K> {
-        val provider = FirestoreDocument.metadataProvider(this::class)
-        var candidate = provider.create<FirestoreMap<K>>(key)
-        candidate = candidate ?: provider.createInnerType()
+        val metadata = this::class.metadata
+        var candidate = metadata?.create<FirestoreMap<K>>(key)
+        candidate = candidate ?: metadata?.createInnerType()
         candidate = candidate ?: FirestoreMap()
         return candidate
     }
 
     protected open fun <K: Any> onCreateFirestoreList(key: String): FirestoreList<K> {
-        val provider = FirestoreDocument.metadataProvider(this::class)
-        var candidate = provider.create<FirestoreList<K>>(key)
-        candidate = candidate ?: provider.createInnerType()
+        val metadata = this::class.metadata
+        var candidate = metadata?.create<FirestoreList<K>>(key)
+        candidate = candidate ?: metadata?.createInnerType()
         candidate = candidate ?: FirestoreList()
         return candidate
     }
 
-    final operator fun set(key: String, value: T) {
+    public operator fun set(key: String, value: T) {
         val result = onSet(key, value)
         /* if (result == null) {
             // Do nothing.
@@ -125,14 +129,14 @@ open class FirestoreMap<T>(
         } else {
             data[key] = result
             dirty.add(key)
-            val resource = FirestoreDocument.metadataProvider(this::class).getBindableResource(key)
+            val resource = this::class.metadata?.getBindableResource(key)
             if (resource != null) notifyPropertyChanged(resource)
         }
     }
 
     internal open fun onSet(key: String, value: T): T = value
 
-    final operator fun get(key: String): T? {
+    public operator fun get(key: String): T? {
         return if (key.contains('.')) {
             val first = key.split('.')[0]
             val second = key.removePrefix("$first.")
@@ -172,9 +176,9 @@ open class FirestoreMap<T>(
         var what = source[property.name] as R
 
         if (what == null) {
-            val provider = FirestoreDocument.metadataProvider(this::class)
-            if (!provider.isNullable(property.name)) {
-                what = provider.create<R>(property.name)!!
+            val metadata = this::class.metadata
+            if (metadata != null && !metadata.isNullable(property.name)) {
+                what = metadata.create<R>(property.name)!!
                 source[property.name] = what
                 // We don't want this to be dirty now! It was just retrieved, not really set.
                 // If we leave it dirty, it would not be updated on next mergeValues().
@@ -240,7 +244,7 @@ open class FirestoreMap<T>(
     internal fun mergeValues(values: Map<String, T>, checkChanges: Boolean, tag: String): Boolean {
         var changed = false
         for ((key, value) in values) {
-            FirestoreLogger.v { "$tag mergeValues: key $key with value $value, dirty: ${isDirty(key)}" }
+            log.v { "$tag mergeValues: key $key with value $value, dirty: ${isDirty(key)}" }
             if (isDirty(key)) continue
             if (value is Map<*, *> && value.keys.all { it is String }) {
                 val child = get(key) ?: createFirestoreMap<Any?>(key) as T // T
@@ -258,7 +262,7 @@ open class FirestoreMap<T>(
                 changed = changed || childChanged
             } else {
                 if (checkChanges && !changed) {
-                    FirestoreLogger.v { "$tag mergeValues: key $key comparing with value ${data[key]}" }
+                    log.v { "$tag mergeValues: key $key comparing with value ${data[key]}" }
                     changed = changed || value != data[key]
                 }
                 data[key] = value
@@ -283,44 +287,46 @@ open class FirestoreMap<T>(
         return result
     }
 
-    override fun describeContents() = 0
+    override fun describeContents(): Int = 0
 
     override fun writeToParcel(parcel: Parcel, flags: Int) {
         val hashcode = hashCode()
         parcel.writeInt(hashcode)
 
         // Write class name
-        FirestoreLogger.i { "Map $hashcode: writing class ${this::class.java.name}" }
+        log.i { "Map $hashcode: writing class ${this::class.java.name}" }
         parcel.writeString(this::class.java.name)
 
         // Write dirty data
-        FirestoreLogger.v { "Map $hashcode: writing dirty count ${dirty.size} and dirty keys ${dirty.toTypedArray().joinToString()} ${dirty.toTypedArray().size}." }
+        log.v { "Map $hashcode: writing dirty count ${dirty.size} and dirty keys ${dirty.toTypedArray().joinToString()} ${dirty.toTypedArray().size}." }
         parcel.writeInt(dirty.size)
         parcel.writeStringArray(dirty.toTypedArray())
 
-        FirestoreLogger.v { "Map $hashcode: writing data size. $size" }
+        log.v { "Map $hashcode: writing data size. $size" }
         parcel.writeInt(size)
         for ((key, value) in data) {
             parcel.writeString(key)
-            FirestoreLogger.v { "Map $hashcode: writing value for key $key..." }
-            FirestoreParcelers.write(parcel, value, hashcode.toString())
+            log.v { "Map $hashcode: writing value for key $key..." }
+            parcel.writeValue(value, hashcode.toString())
         }
 
         val bundle = Bundle()
         onWriteToBundle(bundle)
-        FirestoreLogger.v { "Map $hashcode: writing extra bundle. Size is ${bundle.size()}" }
+        log.v { "Map $hashcode: writing extra bundle. Size is ${bundle.size()}" }
         parcel.writeBundle(bundle)
     }
 
-    companion object {
+    public companion object {
+
+        private val LOG = FirestoreLogger("FirestoreMap")
 
         @Suppress("unused")
         @JvmField
-        public val CREATOR = object : Parcelable.ClassLoaderCreator<FirestoreMap<Any?>> {
+        public val CREATOR: Parcelable.Creator<FirestoreMap<Any?>> = object : Parcelable.ClassLoaderCreator<FirestoreMap<Any?>> {
 
             override fun createFromParcel(source: Parcel): FirestoreMap<Any?> {
                 // This should never be called by the framework.
-                FirestoreLogger.e { "Map: received call to createFromParcel without classLoader." }
+                LOG.e { "Map: received call to createFromParcel without classLoader." }
                 return createFromParcel(source, FirestoreMap::class.java.classLoader!!)
             }
 
@@ -330,23 +336,23 @@ open class FirestoreMap<T>(
 
                 // Read class and create the map object.
                 val klass = Class.forName(parcel.readString()!!)
-                FirestoreLogger.i { "Map $hashcode: read class ${klass.simpleName}" }
+                LOG.i { "Map $hashcode: read class ${klass.simpleName}" }
                 val firestoreMap = klass.newInstance() as FirestoreMap<Any?>
 
                 // Read dirty data
                 val dirty = Array(parcel.readInt()) { "" }
                 parcel.readStringArray(dirty)
-                FirestoreLogger.v { "Map $hashcode: read dirty count ${dirty.size} and array ${dirty.joinToString()}" }
+                LOG.v { "Map $hashcode: read dirty count ${dirty.size} and array ${dirty.joinToString()}" }
 
                 // Read actual data
                 val count = parcel.readInt()
-                FirestoreLogger.v { "Map $hashcode: read data size $count" }
+                LOG.v { "Map $hashcode: read data size $count" }
 
                 val values = HashMap<String, Any?>(count)
                 repeat(count) {
                     val key = parcel.readString()!!
-                    FirestoreLogger.v { "Map $hashcode: reading value for key $key..." }
-                    values[key] = FirestoreParcelers.read(parcel, loader, hashcode.toString())
+                    LOG.v { "Map $hashcode: reading value for key $key..." }
+                    values[key] = parcel.readValue(loader, hashcode.toString())
                 }
 
                 // Set both
@@ -356,9 +362,9 @@ open class FirestoreMap<T>(
                 firestoreMap.data.putAll(values)
 
                 // Read the extra bundle
-                FirestoreLogger.v { "Map $hashcode: reading extra bundle." }
+                LOG.v { "Map $hashcode: reading extra bundle." }
                 val bundle = parcel.readBundle(loader)
-                FirestoreLogger.v { "Map $hashcode: read extra bundle, size ${bundle?.size()}" }
+                LOG.v { "Map $hashcode: read extra bundle, size ${bundle?.size()}" }
                 firestoreMap.onReadFromBundle(bundle!!)
                 return firestoreMap
             }
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreParceler.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreParceler.kt
deleted file mode 100644
index ca7e984..0000000
--- a/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreParceler.kt
+++ /dev/null
@@ -1,16 +0,0 @@
-package com.otaliastudios.firestore
-
-import android.os.Parcel
-
-interface FirestoreParceler<T: Any> {
-
-    /**
-     * Writes the [T] instance state to the [parcel].
-     */
-    fun write(data: T, parcel: Parcel, flags: Int)
-
-    /**
-     * Reads the [T] instance state from the [parcel], constructs the new [T] instance and returns it.
-     */
-    fun create(parcel: Parcel): T
-}
\ No newline at end of file
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreParcelers.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreParcelers.kt
deleted file mode 100644
index 37baecd..0000000
--- a/firestore/src/main/kotlin/com/otaliastudios/firestore/FirestoreParcelers.kt
+++ /dev/null
@@ -1,79 +0,0 @@
-/*
- * Copyright (c) 2018 Otalia Studios. Author: Mattia Iavarone.
- */
-
-package com.otaliastudios.firestore
-
-import android.os.Parcel
-import com.google.firebase.Timestamp
-import com.google.firebase.firestore.DocumentReference
-import com.google.firebase.firestore.FieldValue
-import com.google.firebase.firestore.FirebaseFirestore
-import kotlin.reflect.KClass
-
-/**
- * Parceling engine.
- */
-object FirestoreParcelers {
-
-    internal val MAP = mutableMapOf<String, FirestoreParceler<*>>()
-
-    fun <T: Any> add(klass: KClass<T>, parceler: FirestoreParceler<T>) {
-        MAP[klass.java.name] = parceler
-    }
-
-    private const val NULL = 0
-    private const val PARCELER = 1
-    private const val VALUE = 2
-
-    internal fun write(parcel: Parcel, value: Any?, tag: String) {
-        if (value == null) {
-            FirestoreLogger.v { "$tag writeParcel: value is null." }
-            parcel.writeInt(NULL)
-            return
-        }
-        val klass = value::class.java.name
-        if (MAP.containsKey(klass)) {
-            FirestoreLogger.v { "$tag writeParcel: value $value will be written with parceler for class $klass." }
-            parcel.writeInt(PARCELER)
-            parcel.writeString(klass)
-            @Suppress("UNCHECKED_CAST")
-            val parceler = MAP[klass] as FirestoreParceler<Any>
-            parceler.write(value, parcel, 0)
-            return
-        }
-        try {
-            FirestoreLogger.v { "$tag writeParcel: value $value will be written with writeValue()." }
-            parcel.writeInt(VALUE)
-            parcel.writeValue(value)
-        } catch (e: Exception) {
-            FirestoreLogger.e(e) { "Could not write value $value. You need to add a FirestoreParceler." }
-            throw e
-        }
-    }
-
-    internal fun read(parcel: Parcel, loader: ClassLoader, tag: String): Any? {
-        val what = parcel.readInt()
-        if (what == NULL) {
-            FirestoreLogger.v { "$tag readParcel: value is null." }
-            return null
-        }
-        if (what == PARCELER) {
-            val klass = parcel.readString()!!
-            FirestoreLogger.v { "$tag readParcel: value will be read by parceler $klass." }
-            @Suppress("UNCHECKED_CAST")
-            val parceler = MAP[klass] as FirestoreParceler<Any>
-            return parceler.create(parcel)
-        }
-        if (what == VALUE) {
-            val read = parcel.readValue(loader)
-            FirestoreLogger.v { "$tag readParcel: value was read by readValue: $read." }
-            return read
-        }
-        val e = IllegalStateException("$tag Error while reading parcel. Unexpected control int: $what")
-        FirestoreLogger.e(e) { e.message!! }
-        throw e
-    }
-
-
-}
\ No newline at end of file
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/batch/FirestoreBatchWrite.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/batch/FirestoreBatchWrite.kt
deleted file mode 100644
index 027ea64..0000000
--- a/firestore/src/main/kotlin/com/otaliastudios/firestore/batch/FirestoreBatchWrite.kt
+++ /dev/null
@@ -1,26 +0,0 @@
-package com.otaliastudios.firestore.batch
-
-import com.google.android.gms.tasks.Task
-import com.google.android.gms.tasks.Tasks
-import com.otaliastudios.firestore.FirestoreDocument
-
-class FirestoreBatchWrite internal constructor() {
-
-    private val batch = FirestoreDocument.FIRESTORE.batch()
-    private val writer = FirestoreBatchWriter(batch)
-
-    fun perform(action: FirestoreBatchWriter.() -> Unit): FirestoreBatchWrite {
-        action(writer)
-        return this
-    }
-
-    fun commit(): Task<Unit> {
-        return batch.commit().addOnSuccessListener {
-            writer.ops.forEach { it.notifySuccess() }
-        }.addOnFailureListener {
-            writer.ops.forEach { it.notifyFailure() }
-        }.onSuccessTask {
-            Tasks.forResult(Unit)
-        }
-    }
-}
\ No newline at end of file
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/batch/FirestoreBatchWriter.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/batch/FirestoreBatchWriter.kt
deleted file mode 100644
index 2520c18..0000000
--- a/firestore/src/main/kotlin/com/otaliastudios/firestore/batch/FirestoreBatchWriter.kt
+++ /dev/null
@@ -1,17 +0,0 @@
-package com.otaliastudios.firestore.batch
-
-import com.google.firebase.firestore.WriteBatch
-import com.otaliastudios.firestore.FirestoreDocument
-
-class FirestoreBatchWriter internal constructor(private val batch: WriteBatch) {
-
-    internal val ops = mutableListOf<FirestoreDocument.BatchOp>()
-
-    fun save(document: FirestoreDocument) {
-        ops.add(document.save(batch))
-    }
-
-    public fun delete(document: FirestoreDocument) {
-        ops.add(document.delete(batch))
-    }
-}
\ No newline at end of file
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/batchWrite.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/batchWrite.kt
new file mode 100644
index 0000000..00482e4
--- /dev/null
+++ b/firestore/src/main/kotlin/com/otaliastudios/firestore/batchWrite.kt
@@ -0,0 +1,65 @@
+package com.otaliastudios.firestore
+
+import com.google.android.gms.tasks.Task
+import com.google.android.gms.tasks.Tasks
+import com.google.firebase.firestore.WriteBatch
+
+
+/**
+ * Initiates a batch write operation.
+ */
+@Suppress("unused")
+public fun batchWrite(updates: FirestoreBatchWriter.() -> Unit): Task<Unit> {
+    return FirestoreBatchWrite().run {
+        perform(updates)
+        commit()
+    }
+}
+
+public class FirestoreBatchWriter internal constructor(private val batch: WriteBatch) {
+
+    internal val ops = mutableListOf<FirestoreBatchOp>()
+
+    /**
+     * Adds a document save to the batch operation.
+     */
+    @Suppress("unused")
+    public fun save(document: FirestoreDocument) {
+        ops.add(document.save(batch))
+    }
+
+
+    /**
+     * Adds a document deletion to the batch operation.
+     */
+    @Suppress("unused")
+    public fun delete(document: FirestoreDocument) {
+        ops.add(document.delete(batch))
+    }
+}
+
+private class FirestoreBatchWrite {
+
+    private val batch = FIRESTORE.batch()
+    private val writer = FirestoreBatchWriter(batch)
+
+    fun perform(action: FirestoreBatchWriter.() -> Unit): FirestoreBatchWrite {
+        action(writer)
+        return this
+    }
+
+    fun commit(): Task<Unit> {
+        return batch.commit().addOnSuccessListener {
+            writer.ops.forEach { it.notifySuccess() }
+        }.addOnFailureListener {
+            writer.ops.forEach { it.notifyFailure() }
+        }.onSuccessTask {
+            Tasks.forResult(Unit)
+        }
+    }
+}
+
+internal interface FirestoreBatchOp {
+    fun notifySuccess()
+    fun notifyFailure()
+}
\ No newline at end of file
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/cache.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/cache.kt
new file mode 100644
index 0000000..4bd3066
--- /dev/null
+++ b/firestore/src/main/kotlin/com/otaliastudios/firestore/cache.kt
@@ -0,0 +1,33 @@
+package com.otaliastudios.firestore
+
+import android.util.LruCache
+import kotlin.reflect.KClass
+
+public object FirestoreCache {
+    // TODO make size configurable
+    private val cache = LruCache<String, FirestoreDocument>(100)
+
+    @Suppress("UNCHECKED_CAST")
+    public fun <T: FirestoreDocument> get(id: String, type: KClass<T>): T? {
+        val cached = cache[id] ?: return null
+        require(type.isInstance(cached)) { "Cached object is not of the given type: $type / ${cached::class}"}
+        return cached as T
+    }
+
+    @Suppress("unused")
+    public inline operator fun <reified T: FirestoreDocument> get(id: String): T? {
+        return get(id, T::class)
+    }
+
+    internal operator fun <T: FirestoreDocument> set(id: String, value: T) {
+        cache.put(id, value)
+    }
+
+    internal fun remove(id: String) {
+        cache.remove(id)
+    }
+}
+
+public enum class FirestoreCacheState {
+    FRESH, CACHED_EQUAL, CACHED_CHANGED
+}
\ No newline at end of file
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/config.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/config.kt
new file mode 100644
index 0000000..6101041
--- /dev/null
+++ b/firestore/src/main/kotlin/com/otaliastudios/firestore/config.kt
@@ -0,0 +1,19 @@
+package com.otaliastudios.firestore
+
+import android.util.LruCache
+import com.google.firebase.firestore.ktx.firestore
+import com.google.firebase.ktx.Firebase
+import com.otaliastudios.firestore.parcel.DocumentReferenceParceler
+import com.otaliastudios.firestore.parcel.FieldValueParceler
+import com.otaliastudios.firestore.parcel.TimestampParceler
+import com.otaliastudios.firestore.parcel.registerParceler
+
+// TODO make it configurable (FirebaseApp)
+internal val FIRESTORE by lazy {
+    Firebase.firestore.also {
+        // One time setup
+        registerParceler(DocumentReferenceParceler)
+        registerParceler(TimestampParceler)
+        registerParceler(FieldValueParceler)
+    }
+}
\ No newline at end of file
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/metadata.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/metadata.kt
new file mode 100644
index 0000000..0c633ed
--- /dev/null
+++ b/firestore/src/main/kotlin/com/otaliastudios/firestore/metadata.kt
@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2018 Otalia Studios. Author: Mattia Iavarone.
+ */
+
+package com.otaliastudios.firestore
+
+import androidx.annotation.Keep
+import kotlin.reflect.KClass
+
+// Keep in sync with compiler!
+// And also proguard rules
+@Keep
+public interface FirestoreMetadata {
+    public fun <T> create(key: String): T?
+    public fun isNullable(key: String): Boolean
+    public fun getBindableResource(key: String): Int?
+    public fun <T> createInnerType(): T?
+
+    public companion object {
+        public const val SUFFIX: String = "MetadataImpl"
+    }
+}
+
+private val log = FirestoreLogger("Metadata")
+
+private val METADATA
+        = mutableMapOf<String, FirestoreMetadata>()
+
+internal val KClass<*>.metadata : FirestoreMetadata? get() {
+    val name = java.name
+    if (!METADATA.containsKey(name)) {
+        try {
+            val classPackage = java.`package`!!.name
+            val className = java.simpleName
+            val metadata = Class.forName("$classPackage.$className${FirestoreMetadata.SUFFIX}")
+            METADATA[name] = metadata.newInstance() as FirestoreMetadata
+        } catch (e: Exception) {
+            log.w(e) { "Error while fetching class metadata." }
+        }
+    }
+    return METADATA[name]
+}
\ No newline at end of file
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/DocumentReferenceParceler.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/parcel/DocumentReferenceParceler.kt
similarity index 65%
rename from firestore/src/main/kotlin/com/otaliastudios/firestore/DocumentReferenceParceler.kt
rename to firestore/src/main/kotlin/com/otaliastudios/firestore/parcel/DocumentReferenceParceler.kt
index 0e97a3d..b9e4550 100644
--- a/firestore/src/main/kotlin/com/otaliastudios/firestore/DocumentReferenceParceler.kt
+++ b/firestore/src/main/kotlin/com/otaliastudios/firestore/parcel/DocumentReferenceParceler.kt
@@ -1,14 +1,15 @@
-package com.otaliastudios.firestore
+package com.otaliastudios.firestore.parcel
 
 import android.os.Parcel
 import com.google.firebase.firestore.DocumentReference
 import com.google.firebase.firestore.FirebaseFirestore
+import com.otaliastudios.firestore.parcel.FirestoreParceler
 
 /**
  * Parcels a possibly null DocumentReference.
- * Uses FirebaseFirestore.getInstance().
+ * Note that it uses [FirebaseFirestore.getInstance] to do so.
  */
-object DocumentReferenceParceler: FirestoreParceler<DocumentReference> {
+public object DocumentReferenceParceler: FirestoreParceler<DocumentReference> {
 
     override fun create(parcel: Parcel): DocumentReference {
         return FirebaseFirestore.getInstance().document(parcel.readString()!!)
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/FieldValueParceler.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/parcel/FieldValueParceler.kt
similarity index 62%
rename from firestore/src/main/kotlin/com/otaliastudios/firestore/FieldValueParceler.kt
rename to firestore/src/main/kotlin/com/otaliastudios/firestore/parcel/FieldValueParceler.kt
index 6f51f65..4e969e2 100644
--- a/firestore/src/main/kotlin/com/otaliastudios/firestore/FieldValueParceler.kt
+++ b/firestore/src/main/kotlin/com/otaliastudios/firestore/parcel/FieldValueParceler.kt
@@ -1,18 +1,18 @@
-package com.otaliastudios.firestore
+package com.otaliastudios.firestore.parcel
 
 import android.os.Parcel
 import com.google.firebase.firestore.FieldValue
+import com.otaliastudios.firestore.parcel.FirestoreParceler
 
 /**
- * Parcels a FieldValue
+ * Parcels a [FieldValue].
  */
-object FieldValueParceler: FirestoreParceler<FieldValue> {
+public object FieldValueParceler: FirestoreParceler<FieldValue> {
 
     override fun create(parcel: Parcel): FieldValue {
-        val what = parcel.readString()
-        when (what) {
-            "delete" -> return FieldValue.delete()
-            "timestamp" -> return FieldValue.serverTimestamp()
+        return when (val what = parcel.readString()) {
+            "delete" -> FieldValue.delete()
+            "timestamp" -> FieldValue.serverTimestamp()
             else -> throw RuntimeException("Unknown FieldValue value: $what")
         }
     }
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/parcel/FirestoreParceler.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/parcel/FirestoreParceler.kt
new file mode 100644
index 0000000..e2f4116
--- /dev/null
+++ b/firestore/src/main/kotlin/com/otaliastudios/firestore/parcel/FirestoreParceler.kt
@@ -0,0 +1,35 @@
+package com.otaliastudios.firestore.parcel
+
+import android.os.Parcel
+import kotlin.reflect.KClass
+
+public interface FirestoreParceler<T: Any> {
+
+    /**
+     * Writes the [T] instance state to the [parcel].
+     */
+    public fun write(data: T, parcel: Parcel, flags: Int)
+
+    /**
+     * Reads the [T] instance state from the [parcel], constructs the new [T] instance and returns it.
+     */
+    public fun create(parcel: Parcel): T
+
+    public companion object {
+        /**
+         * Registers a new [FirestoreParceler].
+         */
+        @Suppress("unused")
+        public fun <T: Any> register(klass: KClass<T>, parceler: FirestoreParceler<T>) {
+            registerParceler(klass, parceler)
+        }
+
+        /**
+         * Registers a new [FirestoreParceler].
+         */
+        @Suppress("unused")
+        public inline fun <reified T: Any> register(parceler: FirestoreParceler<T>) {
+            registerParceler(T::class, parceler)
+        }
+    }
+}
\ No newline at end of file
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/TimestampParceler.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/parcel/TimestampParceler.kt
similarity index 70%
rename from firestore/src/main/kotlin/com/otaliastudios/firestore/TimestampParceler.kt
rename to firestore/src/main/kotlin/com/otaliastudios/firestore/parcel/TimestampParceler.kt
index 614ae4c..2612ae0 100644
--- a/firestore/src/main/kotlin/com/otaliastudios/firestore/TimestampParceler.kt
+++ b/firestore/src/main/kotlin/com/otaliastudios/firestore/parcel/TimestampParceler.kt
@@ -1,12 +1,13 @@
-package com.otaliastudios.firestore
+package com.otaliastudios.firestore.parcel
 
 import android.os.Parcel
 import com.google.firebase.Timestamp
+import com.otaliastudios.firestore.parcel.FirestoreParceler
 
 /**
  * Parcels a possibly null Timestamp.
  */
-object TimestampParceler: FirestoreParceler<Timestamp> {
+public object TimestampParceler: FirestoreParceler<Timestamp> {
 
     override fun create(parcel: Parcel): Timestamp {
         return Timestamp(parcel.readLong(), parcel.readInt())
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/parcel/api.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/parcel/api.kt
new file mode 100644
index 0000000..74b9dd9
--- /dev/null
+++ b/firestore/src/main/kotlin/com/otaliastudios/firestore/parcel/api.kt
@@ -0,0 +1,76 @@
+package com.otaliastudios.firestore.parcel
+
+import android.os.Parcel
+import com.otaliastudios.firestore.FirestoreLogger
+import kotlin.reflect.KClass
+
+private val PARCELERS = mutableMapOf<String, FirestoreParceler<*>>()
+
+/**
+ * Registers a new [FirestoreParceler].
+ */
+public fun <T: Any> registerParceler(klass: KClass<T>, parceler: FirestoreParceler<T>) {
+    PARCELERS[klass.java.name] = parceler
+}
+
+/**
+ * Registers a new [FirestoreParceler].
+ */
+@Suppress("unused")
+public inline fun <reified T: Any> registerParceler(parceler: FirestoreParceler<T>) {
+    registerParceler(T::class, parceler)
+}
+
+private val log = FirestoreLogger("Parcelers")
+private const val NULL = 0
+private const val PARCELER = 1
+private const val VALUE = 2
+
+internal fun Parcel.writeValue(value: Any?, tag: String) {
+    if (value == null) {
+        log.v { "$tag writeParcel: value is null." }
+        writeInt(NULL)
+        return
+    }
+    val klass = value::class.java.name
+    if (PARCELERS.containsKey(klass)) {
+        log.v { "$tag writeParcel: value $value will be written with parceler for class $klass." }
+        writeInt(PARCELER)
+        writeString(klass)
+        @Suppress("UNCHECKED_CAST")
+        val parceler = PARCELERS[klass] as FirestoreParceler<Any>
+        parceler.write(value, this, 0)
+        return
+    }
+    try {
+        log.v { "$tag writeParcel: value $value will be written with writeValue()." }
+        writeInt(VALUE)
+        writeValue(value)
+    } catch (e: Exception) {
+        log.e(e) { "Could not write value $value. You need to add a FirestoreParceler." }
+        throw e
+    }
+}
+
+internal fun Parcel.readValue(loader: ClassLoader, tag: String): Any? {
+    val what = readInt()
+    if (what == NULL) {
+        log.v { "$tag readParcel: value is null." }
+        return null
+    }
+    if (what == PARCELER) {
+        val klass = readString()!!
+        log.v { "$tag readParcel: value will be read by parceler $klass." }
+        @Suppress("UNCHECKED_CAST")
+        val parceler = PARCELERS[klass] as FirestoreParceler<Any>
+        return parceler.create(this)
+    }
+    if (what == VALUE) {
+        val read = readValue(loader)
+        log.v { "$tag readParcel: value was read by readValue: $read." }
+        return read
+    }
+    val e = IllegalStateException("$tag Error while reading parcel. Unexpected control int: $what")
+    log.e(e) { e.message!! }
+    throw e
+}
diff --git a/firestore/src/main/kotlin/com/otaliastudios/firestore/snapshots.kt b/firestore/src/main/kotlin/com/otaliastudios/firestore/snapshots.kt
new file mode 100644
index 0000000..52ec2d0
--- /dev/null
+++ b/firestore/src/main/kotlin/com/otaliastudios/firestore/snapshots.kt
@@ -0,0 +1,64 @@
+package com.otaliastudios.firestore
+
+import com.google.firebase.firestore.DocumentSnapshot
+import kotlin.reflect.KClass
+
+private val log = FirestoreLogger("Snapshots")
+
+/**
+ * Converts the given [DocumentSnapshot] to a [FirestoreDocument].
+ * The [cache] boolean tells whether we should inspect the cache before allocating a new object.
+ */
+@Suppress("unused")
+public inline fun <reified T: FirestoreDocument> DocumentSnapshot.toFirestoreDocument(cache: Boolean = true): T {
+    return toFirestoreDocument(T::class, cache)
+}
+
+/**
+ * Converts the given [DocumentSnapshot] to a [FirestoreDocument].
+ * The [cache] boolean tells whether we should inspect the cache before allocating a new object.
+ */
+@Suppress("UNCHECKED_CAST")
+public fun <T: FirestoreDocument> DocumentSnapshot.toFirestoreDocument(type: KClass<T>, cache: Boolean = true): T {
+    var needsCacheState = false
+    val result = if (cache) {
+        val cached = FirestoreCache.get(reference.id, type)
+        if (cached == null) {
+            log.i { "Id ${reference.id} asked for cache. Cache miss." }
+            val new = type.java.newInstance()
+            new.clearDirt() // Clear dirtyness from init().
+            FirestoreCache[reference.id] = new
+            new.cacheState = FirestoreCacheState.FRESH
+            new
+        } else {
+            if (metadata.isFromCache) {
+                log.i { "Id ${reference.id} asked for cache. Was found. Using CACHED_EQUAL because metadata.isFromCache." }
+                cached.cacheState = FirestoreCacheState.CACHED_EQUAL
+            } else {
+                log.i { "Id ${reference.id} asked for cache. Was found. We'll see if something changed." }
+                needsCacheState = true
+            }
+            cached
+        }
+    } else {
+        log.i { "Id ${reference.id} created with no cache." }
+        val new = type.java.newInstance()
+        new.clearDirt() // Clear dirtyness from init().
+        FirestoreCache[reference.id] = new
+        new.cacheState = FirestoreCacheState.FRESH
+        new
+    }
+    result.id = reference.id
+    result.collection = reference.parent.path
+    val changed = result.mergeValues(data!!, needsCacheState, reference.id)
+    if (needsCacheState) {
+        result.cacheState = if (changed) {
+            log.v { "Id ${reference.id} Setting cache state to CACHED_CHANGED." }
+            FirestoreCacheState.CACHED_CHANGED
+        } else {
+            log.v { "Id ${reference.id} Setting cache state to CACHED_EQUAL." }
+            FirestoreCacheState.CACHED_EQUAL
+        }
+    }
+    return result
+}
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index 1b48104..4238311 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.4-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.4-all.zip