You can see the source code & feature list at https://github.com/JaThePlayer/FrostHelper
Wiki at https://github.com/JaThePlayer/FrostHelper/wiki
Requires Celeste 1.4+
For map makers:
If you wish to use the things from here, add a dependency like this to your everest.yaml file:
Dependencies:
- Name: FrostHelper
Version: 1.38.0