head to head · open source
vllm vs langchain4j
vllm has 92,028 GitHub stars, 22,335 forks, 7,953 open issues and last shipped yesterday. langchain4j has 13,116 stars, 2,555 forks, 878 open issues and last shipped 2 days ago. vllm leads on adoption by 602% (92,028 vs 13,116 stars). vllm is written in Python under Apache-2.0; langchain4j is written in Java under Apache-2.0. vllm has attracted 24% as many forks as stars, langchain4j 19%. vllm was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 3 topic tags (gpt, llama, 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 | langchain4j | |
|---|---|---|
| GitHub stars | ★ 92K | ★ 13K |
| License | Apache-2.0 | Apache-2.0 |
| Written in | Python | Java |
| Last push | 2026-09-17 | 2026-09-16 |
| Forks | ⑂ 22K | ⑂ 2.6K |
| 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
pick langchain4j if
- You want the langchain4j feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Java
- You evaluated both and langchain4j fits your workflow better
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.
About langchain4j
LangChain4j is an Apache 2.0, open source, idiomatic Java library for building LLM powered applications on the JVM, aimed at Java developers and enterprise teams who want one unified API over many LLM providers and embedding stores without leaving the Java ecosystem.
read the full langchain4j overview →
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Frequently asked questions
Is vllm or langchain4j more popular?
vllm has 92,028 GitHub stars and langchain4j has 13,116. vllm has the larger community by that measure.
Are vllm and langchain4j free?
Both are open source. vllm is licensed under Apache-2.0 and langchain4j under Apache-2.0. Neither carries a licence fee.
What is the difference between vllm and langchain4j?
vllm is written in Python and langchain4j in Java. 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 langchain4j?
Choose vllm if you want the larger community (92,028 stars) or its Apache-2.0 licence terms. Choose langchain4j if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.