Phoenix
AI observability for traces, evals, and experiments — Elastic-licensed.
About
Phoenix is Arize's AI observability platform for experimentation, evaluation, and troubleshooting: OpenTelemetry-based tracing of LLM app runs, LLM-as-judge evals, versioned datasets and experiments, a prompt playground for comparing models, and PXI — a built-in AI agent for debugging traces. It installs via pip/conda/Docker and is MCP-enabled. License note: the repo is under Elastic License 2.0 — source-available, not OSI open source, despite 'open-source' marketing language. Managed production workflows upsell to Arize AX. 11.8k stars.
What it can do
- **Tracing**: OpenTelemetry-based LLM run tracing with span inspection
- **Evaluations**: response and retrieval evals with LLM judges
- **Datasets & experiments**: versioned examples; track prompt/model/retrieval changes
- **Playground**: optimize prompts, compare models, replay traced calls
- **PXI agent**: built-in AI engineer for debugging traces and iterating prompts
- **MCP + Cursor**: MCP server and one-click Cursor integration
Setup
```bash
pip install arize-phoenix
```
```python
import phoenix as px
px.launch_app() # local UI for traces
```
Instrument with OpenTelemetry (auto-instrumentation for OpenAI/LangChain/LlamaIndex). Docker + Helm for self-host. Docs: arize.com/docs/phoenix.
Prerequisites
Python 3.9+. Optional: Docker for production self-host; API keys for the models you trace.
Use cases
Works with
Trust score — 8/10
Scored 8/10 (verified tier, metrics-v1). Evidence: 11,808 GitHub stars (log-scaled vs catalog peers); last push 0d ago; 100 releases/12mo; 1158 open issues. Manual review: Arize observability (OTel tracing, evals, datasets, playground, PXI agent); 11.8k stars; managed Arize AX is the monetization funnel. License: Elastic License 2.0 — source-available, NOT OSI open source (despite 'open-source' marketing).
★ 11,808 GitHub stars
How the trust score is built
Full methodology →- Adoption · stars/downloads, log-scaled vs peers
- 7.7/10
- Maintenance · recency, releases, issue load
- 8.2/10
- Openness · license + docs
- 7.2/10
- Manual review · sanity read + red-flag check
- 8.0/10
- · 11,808 GitHub stars (log-scaled vs catalog peers)
- · last push 0d ago; 100 releases/12mo; 1158 open issues
- · manual review: Arize observability (OTel tracing, evals, datasets, playground, PXI agent); 11.8k stars; managed Arize AX is the monetization funnel
Sources
Every fact above was checked against these sources. Where a claim comes from the provider and couldn't be independently verified, the text says so.