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TruLens vs Arize Phoenix: catalog facts
TruLens	Arize Phoenix
Free Free and open source.	Freemium Phoenix is free to self-host; Arize AX is a separate managed paid platform.
Windows, macOS, Linux	Web, Self-hosted
OpenTelemetry-native tracing of every agent step Judges explain their scores, not just give numbers	Tracing, evals, prompts and experiments in one tool Runs locally, in Docker or on Kubernetes
Aimed at developers comfortable writing code LLM judges add their own model calls and cost	Source-available license rather than an OSI-approved one Some advanced features are in the separate paid Arize AX product
Downloadable app	Self-hosted, Hosted service
Open source	Closed source
License not stated	License: Elastic-2.0
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 October 1, 2026	Official website Full listing and sources Checked September 26, 2026

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