2D Auto Lip Sync is a Blender addon from Vrengkat that automates mouth-to-audio matching for 2D characters. It works with both Grease Pencil layers and image-based cut-out viseme collections, switching between the two so you can use whichever setup your character uses. Under the hood, it applies FFT frequency tracking to detect vowels and consonants from an audio track.
Beyond mouth shapes, the addon drives a jaw bone with customizable openness for every viseme. Built-in temporal hysteresis smooths the output to prevent flickering mouths and keeps animation stable at any frame rate. Audio sync runs through the Blender Video Sequencer: select your audio strip and click Detect Start Frame. A manual viseme grid lets you punch in specific mouth shapes alongside the automated generator, and the tool is compatible with the Rhubarb Lip Sync engine for phonetic accuracy.
The download includes the addon in Zip format, pre-configured jaw-drop presets for the 12 standard visemes, and step-by-step documentation. It is listed as compatible with Blender 3.0 through 5.1 under the GPL license.