Go memory debug charts.
This package uses chart library Highcharts. It is free for personal and non-commercial use. Please buy a license otherwise.
go get -v -u github.com/mkevac/debugcharts
Just install package and start http server. There is an example program here.
Then go to http://localhost:8080/debug/charts. You should see something like this:
Data is updated every second. We keep data for last day.