Labels 4 is an After Effects utility from Rendertom for managing label colors. With a single button click, you can set or reset label colors and select label groups, and it works across keyframes, layers, and project panel items. You can filter used and unused label colors, and it supports custom label colors alongside shareable label themes.
Beyond color assignment, Labels 4 includes a set of layer utilities tied to label colors. It can create a full-sized Shape Layer or Solid Layer with its color set to the label color, copy a label's HEX value to the clipboard, group layers sharing a color under the topmost matching layer, and parent them to a null. You can push layers with a given label up or down the stack one at a time, and toggle shy or solo for layers by label color.
Labels 4 also works as a script launcher and exposes a Labels API, so you can build your own extensions from the default script snippets or via GitHub. Keyframe label colors are supported in After Effects v22.6 and later.