# Arize Phoenix

> ELv2 self-host AI observability & eval — traces, datasets, playground

**Category:** AI Agents  
**Pricing:** source-available  
**URL:** https://phoenix.arize.com  
**GitHub:** https://github.com/Arize-ai/phoenix  
**Added:** 2026-09-29

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## The Hook

Phoenix is Arize’s self-host AI observability and evaluation stack — traces, embeddings, datasets, and evals when Langfuse is the MIT default and you want Phoenix’s notebook-friendly path.

## What's Good

Elastic License 2.0 (Arize-ai/phoenix). Open inference tracing, embeddings viz, datasets, experiments, and eval helpers; pip/Docker self-host; pairs with Arize AX cloud if you outgrow local. Docs at arize.com/docs/phoenix. ★11,645 on GitHub 2026-09-29.

## The Catch

NOT OSI open source — ELv2 forbids offering Phoenix as a competing hosted SaaS. Vs Langfuse (MIT full-stack self-host) and Braintrust (eval-first freemium): Phoenix is Arize’s ELv2 observability/eval kit with strong notebook/embedding UX, not MIT and not Braintrust’s CI-eval product. Arize cloud is the upsell when you want managed multi-tenant.

## Verdict

ELv2 self-host AI obs/eval when Phoenix’s tracing+evals fit and you accept source-available — not Langfuse MIT, not Braintrust CI-eval.