FCurve Helper is a blender addon designed to help in handling the FCurves, specifically F-Modifiers
Here are the current main features :
2 main operators for Adding and Removing F-Modifiers on all selected FCurves with some specific settings (Add or Modify behaviours to only modified existing F-Modifiers...)
An inspector showing you the selected FCurves and their F-Modifiers. From here you can copy/paste a single Modifier, enable/disable it, or remove it
Here is a link to an overview video of it : https://youtu.be/PVZHrgEGh1E?list=PL57BAmPXpXuPNcd9wgxSUyYcSpBtncnuB