Two of these three are free, and that's the headline. NotebookLM (now branded Gemini Notebook) is free with a Google account — 100 notebooks, 50 sources each, 50 chats a day. ChatGPT Projects landed on the free ChatGPT plan in June 2026. Only Claude Projects requires a paid plan.
| Cost | Best at | |
|---|---|---|
| NotebookLM | free (Plus via Google AI Pro $19.99) | cited Q&A from your sources, audio overviews |
| ChatGPT Projects | free (Plus $20 for the good models) | flexible workspace, wider tooling |
| Claude Projects | Claude Pro $20 | deep reasoning, drafting, 200K-token context |
The three do different jobs. NotebookLM answers strictly from what you upload, with per-sentence citations — it won't wander off your sources, which is exactly what you want for a literature review or grounding a set of documents. It also generates the audio overviews (a two-host podcast about your material) that nothing else here matches. What it won't do is reason freely or help you write.
Claude Projects is the opposite end: it holds ~150K words of project knowledge in context, follows setup instructions, and is genuinely good at drafting and complex reasoning on top of your material — but it's the paid option.
ChatGPT Projects sits in between as a flexible workspace, now free to start, with the caveat that the free tier's models are weaker.
Doing a defined research project where every claim needs a source? NotebookLM, and it's free. Want the AI to reason hard and help you write from your notes? Claude Projects is worth the $20. Want one flexible container for an ongoing body of work? ChatGPT Projects, free to try.