So I made this. Drop in your WhatsApp export zip, get a proper chat interface with all media. The original export stays untouched (important for evidence), bookmarks and annotations layer on top. Voice messages get transcribed locally via Whisper/WebGPU - nothing leaves your machine.
Tested with 18k+ messages, no issues. Runs in browser or as an Electron app for all desktop platforms (Android and iOS coming soon).
Feedback welcome, especially from anyone who's dealt with digital evidence.