head to head · open source
vllm vs LangWatch
vllm has 96,158 GitHub stars, 24,317 forks, 7,953 open issues and last shipped yesterday. LangWatch has 5,004 stars, 426 forks, 939 open issues and last shipped yesterday. vllm leads on adoption by 1,822% (96,158 vs 5,004 stars). vllm is written in Python under Apache-2.0; LangWatch is written in TypeScript under Apache-2.0. vllm has attracted 25% as many forks as stars, LangWatch 9%. LangWatch was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 2 topic tags (gpt, llm), 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
| vllm | LangWatch | |
|---|---|---|
| GitHub stars | ★ 96K | ★ 5.0K |
| License | Apache-2.0 | Apache-2.0 |
| Written in | Python | TypeScript |
| Last push | 2026-11-02 | 2026-11-02 |
| Forks | ⑂ 24K | ⑂ 426 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick vllm if
- You weight community size — 96K 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
pick LangWatch if
- You want the LangWatch feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches TypeScript
- You evaluated both and LangWatch fits your workflow better
About vllm
Easy, fast, and cheap LLM serving for everyone 🔥 We have built a vLLM website to help you get started with vLLM. Please visit vllm.ai to learn more. For events, please visit vllm.ai/events to join us. About vLLM is a fast and easy to use library for LLM inference and serving. Originally developed in the Sky Computing Lab at UC Berkeley, vLLM has grown into one of the most active open source AI projects built and maintained by a diverse community of many dozens of academic institutions and companies from over 2000 contributors. vLLM is fast with: State of the art serving throughput Efficient management of…
About LangWatch
Website · Docs · Discord · Self hosting Why LangWatch? The platform for LLM evaluations and AI agent testing. We help teams test, simulate, evaluate, and monitor LLM powered agents end to end — before release and in production. Built for teams that need regression testing, simulations, and production observability without building custom tooling. End to end agent simulations Run realistic scenarios against your full stack (tools, state, user simulator, judge) and pinpoint where your agents break, and why? down to each decision. Eval + observability + prompts in one loop Trace → dataset → evaluate → optimize…
read the full LangWatch overview →
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Frequently asked questions
Is vllm or LangWatch more popular?
vllm has 96,158 GitHub stars and LangWatch has 5,004. vllm has the larger community by that measure.
Are vllm and LangWatch free?
Both are open source. vllm is licensed under Apache-2.0 and LangWatch under Apache-2.0. Neither carries a licence fee.
What is the difference between vllm and LangWatch?
vllm is written in Python and LangWatch in TypeScript. 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 LangWatch?
Choose vllm if you want the larger community (96,158 stars) or its Apache-2.0 licence terms. Choose LangWatch if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.