Source LM

NotebookLM adds sources one at a time, through a file picker. Source LM adds them in batches, from the browser.

Point it at a JSON export and it packs the records into as many Markdown files as it takes, budgeted under NotebookLM's 500,000-word per-source cap, never splitting a record across files. Re-run it later and only the new records go up. YouTube is the other half: a video, playlist or channel becomes one source per video, with transcripts and optionally the top comment threads, from buttons inside YouTube's own UI. Telegram HTML exports and plain link lists work the same way.

Nothing is written to disk and nothing leaves the machine: the popup builds the files in memory and sends them to the notebook page's own upload endpoint. No backend, no account. Source-available under PolyForm Noncommercial, not open source.

Chrome and Edge. Free plan covers 5 bulk uploads a month; Pro is $29 one-time, not a subscription.