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Galileo vs Arize Phoenix
Quick verdict
Key difference: Arize Phoenix is open-source while Galileo is proprietary.
Side-by-side comparison from the Agent Observability Index: licensing, self-hosting, pricing model and integrations — no vendor copy, primary sources linked.
| Galileo | Arize Phoenix | |
|---|---|---|
| One-liner | Evaluation and guardrails platform whose in-house Luna-2 small judge models target low-cost, low-latency scoring of agentic workloads. | Open-source, OpenTelemetry-based tracing and evaluation library that runs locally or self-hosted, serving as the OSS on-ramp to Arize's enterprise platform. |
| Category | Evals & Testing | Observability & Tracing |
| OpenTelemetry-native | — | Yes |
| Open source | No | Yes |
| Self-hostable | Yes | Yes |
| Pricing model | freemium | free |
| Pricing notes | Free tier added in 2025; enterprise pricing custom | Fully free OSS (Elastic License v2); hosted Phoenix Cloud has a free tier |
| Frameworks | langchain, openai-sdk, llamaindex, opentelemetry | openai-sdk, langchain, llamaindex, dspy, opentelemetry, smolagents |
| GitHub stars | — | 10.1k |
| Maturity (GitHub signal) | — (no public repo) | 90/100 (Mature) |
| Funding / ownership | $45M Series B (Scale Venture Partners, 2024), $68M total | Backed by Arize AI ($70M Series C, Feb 2025) |
How to choose
- Choose Arize Phoenix if open-source licensing or full data control is a hard requirement.
- Both link to primary pricing sources below — verify current tiers before committing; this market shifts monthly.
Sources: Galileo · Arize Phoenix
Frequently asked questions
Is Galileo or Arize Phoenix open source?
Galileo: No. Arize Phoenix: Yes.
Can Galileo and Arize Phoenix be self-hosted?
Galileo: Yes. Arize Phoenix: Yes.
Galileo vs Arize Phoenix: which should I choose?
Key difference: Arize Phoenix is open-source while Galileo is proprietary.