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Nanobrowser vs Fellou: catalog facts
Nanobrowser	Fellou
Free Free and open source; you pay your chosen LLM provider for API usage.	Freemium Free to download, with paid plans for heavier agent use.
Browser extension	Windows, macOS
Runs inside your own browser Bring your own LLM API key	Agent can run multi-step tasks across several websites Shows an editable action plan before it acts
Needs a paid API key from a model provider Chrome-focused	Browser itself is closed source Agent actions depend on AI services and an internet connection
Browser extension	Downloadable app
Open source	Closed source
License not stated	License not stated
No account needed	Not stated if an account is needed
Needs internet	Needs internet
Official website Full listing and sources Checked September 26, 2026	Official website Full listing and sources Checked September 23, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.