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Arize Phoenix vs Promptfoo: catalog facts
Arize Phoenix	Promptfoo
Freemium Phoenix is free to self-host; Arize AX is a separate managed paid platform.	Freemium The open-source CLI is free; enterprise features are sold separately.
Web, Self-hosted	Command line
Tracing, evals, prompts and experiments in one tool Runs locally, in Docker or on Kubernetes	Runs from the command line with a single npx command Compares prompts and models side by side
Source-available license rather than an OSI-approved one Some advanced features are in the separate paid Arize AX product	Red-teaming features are intended for authorized testing of your own applications Some reporting features belong to the paid enterprise edition
Self-hosted, Hosted service	Downloadable app
Closed source	Open source
License: Elastic-2.0	License not stated
Not stated if an account is needed	Not stated if an account is needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked September 26, 2026	Official website Full listing and sources Checked September 26, 2026

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