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

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