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Petal vs PaperQA2: catalog facts
Petal	PaperQA2
Freemium Free to start, with paid options for more use.	Free Free and open source under the Apache 2.0 licence; model API usage may cost extra.
Web	Command line
Answers cite the source documents Document storage with automatic metadata extraction	Answers include citations to the source documents Fetches paper metadata with citation counts and retraction checks
Documents are stored in Petal's cloud Requires an account	Needs a language model, either through an API or run locally Setup and tuning assume comfort with Python
Web application	Downloadable app
Closed source	Open source
License not stated	License: Apache-2.0
Account needed	Not stated if an account is needed
Needs internet	Not stated if it works offline
Official website Full listing and sources Checked September 26, 2026	Official website Full listing and sources Checked October 2, 2026

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