LM Subs

Setup

Interactive setup wizard

The wizard talks to the extension directly. It confirms LM Subs is installed, detects whether the icon is pinned, and tests your key with a short request so you know captions will work before you open NotebookLM.

Three checks, in order

  1. Extension detected: the page pings the extension and reports the installed version.
  2. Toolbar pinned: if the icon is hidden in Chrome's puzzle menu, the page shows exactly where to find it.
  3. Key saved and tested: paste a Groq, Mistral, or local Whisper URL and run a real test transcription.

If the extension is not detected

Most detection failures come from loading the wrong folder. Chrome wants the folder that holds manifest.json directly, not a parent folder that contains it. Reload the extension from chrome://extensions after unzipping, then refresh this page.

After setup

Open Google NotebookLM, play a Video Overview, and press CC in the play bar. Captions generate in a few seconds, the transcript drawer opens with T, and you can export SRT, VTT, TXT, MD, CSV or JSON from the caption menu. Audio Overview podcasts caption the same way and keep both host labels.

If you would rather read than click, the setup guide covers the same steps with screenshots, and the Video Overview walkthrough goes deeper on the caption controls.