AnimAide was an early Graph Editor add-on for Blender that featured curveTools, animOffset, and KeyManager. It's no longer maintained by its developer, however, the Blend functions were implemented into Blender. curveTools includes many methods for tweening your selected keyframes to a specific value. animOffset propogates changes to an object to all F-Curves. KeyManager helps you to shift and insert keys, select and edit keyframe handles or label them as Keyframes, Breakdown, Jitter, or Extreme.

Though the add-on is no longer maintain, the curveTools options were added to native Blender in version 4.0. They can be found under the Key > Blend menu.

GraphKit offers much more than this and is still being developed.

TWEEN
There is redundancy between the functionality of GraphKit's Tween and the Blend options of curveTools/native Blender. The Tween in GraphKit shares the Blend methods of 'Breakdown', 'Blend to Neighbor,' and 'Blend to Default.' It currently doesn't have the other Blend options. 

The continued inclusion of a Tween slider in GraphKit is to offer a simple Tween machine from the user interface instead of a menu or keyboard shortcut. GraphKit's Tween slider has preset buttons in increments of 25% that you can use to precisely create a Tween keyframe (including overshoots).

AMPLIFY
GraphKit's Amplify feature and the Push Pull Blend command are similar, however, Amplify offers more options: amplifying entire selected F-Curves or keyframes from their Bounding Box 'Center', 'First Keyframe', 'Last Keyframe', 'Maximum Keyframe', or 'Minimum Keyframe'. Push Pull only modifies selected keys and does not offer the pivot point options. The native Blender Scale Average Blend command is similar to Amplify's Bounding Box 'Center' pivot point.

CORE FEATURES
GraphKit offers many more unique core features besides a Tween machine in the UI and Amplify options: Distribute, Divide, Fade, Flatten Holds, Hold, Overlap, Perfect Loop, Randomize, and Range to Loop.

SELECT & SOLO

On top of the core features, GraphKit includese F-Curve Selection and Solo commands: Select All by Object Type, Solo All by Object Type, Select F-Curves by Left/Right Side, Select Random F-Curves, and Select Objects/Pose Bones from Selected F-Curves.

CHANNEL TOGGLES

GraphKit also includes essential channel toggles for the Graph Editor: Toggle All Pins, Hide All F-Curves, Toggle All Modifiers, Mute All F-Curves, and Lock All F-Curves.

SUMMARY
GraphKit, a powerful add-on for Blender's Graph Editor, offers a comprehensive suite of features designed to enhance animation workflow. While AnimAide, an earlier add-on, provided animation curve functionalities, it is no longer maintained, and its Blend features have been integrated into native Blender. GraphKit, however, surpasses these capabilities with its 12 core features. Moreover, GraphKit enhances user experience with features such as F-Curve Selection and Solo commands, as well as essential channel toggles for efficient editing in the Graph Editor. With ongoing development and a commitment to innovation, GraphKit stands out as a versatile and superior solution for animation professionals within Blender.