head to head · open source
Langfuse vs Arize Phoenix
Langfuse has 36,898 GitHub stars, 4,146 forks, 926 open issues and last shipped yesterday. Arize Phoenix has 12,106 stars, 1,258 forks, 970 open issues and last shipped yesterday. Langfuse leads on adoption by 205% (36,898 vs 12,106 stars). Langfuse is written in TypeScript under a custom or non-standard licence; Arize Phoenix is written in Python under a custom or non-standard licence. Langfuse has attracted 11% as many forks as stars, Arize Phoenix 10%. Arize Phoenix was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 3 topic tags (langchain, llm-evaluation, llmops), so they are genuine substitutes rather than adjacent tools.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| Langfuse | Arize Phoenix | |
|---|---|---|
| GitHub stars | ★ 37K | ★ 12K |
| License | Custom / other | Custom / other |
| Written in | TypeScript | Python |
| Last push | 2026-11-02 | 2026-11-02 |
| Forks | ⑂ 4.1K | ⑂ 1.3K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Langfuse if
- You weight community size — 37K stars and counting
- You want the Custom / other license terms
- Your stack matches TypeScript
- You value the larger contributor base for long-term maintenance
pick Arize Phoenix if
- You want the Arize Phoenix feature set and don't need the biggest community
- You prefer the Custom / other license terms
- Your stack matches Python
- You evaluated both and Arize Phoenix fits your workflow better
About Langfuse
Langfuse Cloud · Self Host · Demo Docs · Report Bug · Feature Request · Changelog · Roadmap · Langfuse is an open source LLM engineering platform. It helps teams collaboratively develop, monitor, evaluate, and debug AI applications. Langfuse can be self hosted in minutes and is battle tested . Proudly made with ClickHouse open source database. 🧑💻 We're hiring Langfuse is growing fast (we doubled the team in the last 6 months) since January 2026 we're part of ClickHouse, we're hiring engineering hybrid across the EU. We hire engineers who love open source and great developer experiences. See open roles → ✨…
read the full Langfuse overview →
About Arize Phoenix
English · 简体中文 Arize Phoenix is Arize's open source AI observability platform designed for experimentation, evaluation, and troubleshooting. For managed production workflows, Arize also offers Arize AX. Phoenix provides: Tracing Trace your LLM application's runtime using OpenTelemetry based instrumentation. Evaluation Leverage LLMs to benchmark your application's performance using response and retrieval evals. Datasets Create versioned datasets of examples for experimentation, evaluation, and fine tuning. Experiments Track and evaluate changes to prompts, LLMs, and retrieval. Playground Optimize prompts, compare…
read the full Arize Phoenix overview →
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Frequently asked questions
Is Langfuse or Arize Phoenix more popular?
Langfuse has 36,898 GitHub stars and Arize Phoenix has 12,106. Langfuse has the larger community by that measure.
Are Langfuse and Arize Phoenix free?
Neither Langfuse nor Arize Phoenix declares a licence in this registry, so check each project's own repository before relying on either for a commercial use. Both are free to self-host.
What is the difference between Langfuse and Arize Phoenix?
Langfuse is written in TypeScript and Arize Phoenix in Python. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Langfuse or Arize Phoenix?
Choose Langfuse if you want the larger community (36,898 stars) or its Custom / other licence terms. Choose Arize Phoenix if its feature set, stack or Custom / other licence fits better. Both are self-hostable.