Steam Redeem is Chrome, Edge, Firefox and Opera extension that detects Steam keys in a web-page and injects a 'Redeem' button so you can quickly redeem/activate Steam keys in your browser. If you have a page with several Steam keys visible, pressing the Steam Redeem logo next to your address bar will automatically bulk redeem all keys visible on the page.
Presently only Humble Bundle is supported and we're missing a lot of useful features, like tracking of previously redeemed keys. Please take a look at my other (Mac only) Humble Bundle Key Redeemer to get an idea of what sort of functionality will be supported. However, in general this solution is already much more robust, and most importantly cross-platform.
First you need Node.js and Yarn. Then you can build with:
yarn
yarn build
the "unpacked" extensions will be built into the build/ sub-directory.