head to head · open source

vllm vs Arize Phoenix

vllm has 92,202 GitHub stars, 22,428 forks, 7,953 open issues and last shipped today. Arize Phoenix has 11,544 stars, 1,140 forks, 970 open issues and last shipped yesterday. vllm leads on adoption by 699% (92,202 vs 11,544 stars). vllm is written in Python under Apache-2.0; Arize Phoenix is written in Python under a custom or non-standard licence. vllm has attracted 24% as many forks as stars, Arize Phoenix 10%. vllm was the more recently maintained of the two, and both are self-hostable with no licence fee.

Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.

vllm ★ 92K Arize Phoenix ★ 12K category AI & Machine Learning

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Side by side

	vllm	Arize Phoenix
GitHub stars	★ 92K	★ 12K
License	Apache-2.0	Custom / other
Written in	Python	Python
Last push	2026-09-20	2026-09-19
Forks	⑂ 22K	⑂ 1.1K
Self-hosting	Yes	Yes
Data ownership	Your server	Your server

pick vllm if

You weight community size — 92K stars and counting
You want the Apache-2.0 license terms
Your stack matches Python
You value the larger contributor base for long-term maintenance

full vllm profile →

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

full Arize Phoenix profile →

About vllm

vLLM is a high throughput, memory efficient Python library for LLM inference and serving, built for ML engineers and platform teams who need to run open weight models on their own hardware at production scale.

read the full vllm overview →

About Arize Phoenix

Arize Phoenix is an open source AI observability platform for experimentation, evaluation, and troubleshooting. It lives in the machine learning infrastructure ecosystem and is written in Python. The project provides tracing, evaluation, datasets, experiments, prompt management, and a playground for LLM applications.

read the full Arize Phoenix overview →

More in AI & Machine Learning

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Frequently asked questions

Is vllm or Arize Phoenix more popular?

vllm has 92,202 GitHub stars and Arize Phoenix has 11,544. vllm has the larger community by that measure.

Are vllm and Arize Phoenix free?

Both are open source. vllm is licensed under Apache-2.0, and Arize Phoenix has no licence declared in this registry. Both are free to self-host.

What is the difference between vllm and Arize Phoenix?

vllm is written in Python 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, vllm or Arize Phoenix?

Choose vllm if you want the larger community (92,202 stars) or its Apache-2.0 licence terms. Choose Arize Phoenix if its feature set, stack or Custom / other licence fits better. Both are self-hostable.