What is vLLM?
vLLM is an open-source engine for running large language models (LLMs) for inference and serving. The documentation covers offline inference from Python, an OpenAI-compatible online server, and deployment options including Docker, Kubernetes, and Helm. It also covers distributed setups using data, expert, and context parallelism, and integrations with frameworks such as LangChain, LlamaIndex, Ray Serve, and Open WebUI.
In practice, you install vLLM on your own GPU, CPU, or TPU hardware, load a supported model, and either run batch generation in code or start a server that accepts OpenAI-style API requests. The docs also describe features such as automatic prefix caching, LoRA adapters, speculative decoding, structured outputs, tool calling, multimodal inputs, pooling models for embeddings and scoring, and training-related reinforcement learning workflows.
Key features
- Offline batch inference from Python
- OpenAI-compatible online server
- Automatic prefix caching
- LoRA adapter support
- Speculative decoding and structured outputs
- Deployment with Docker, Kubernetes and Helm
Who is it for
- ML engineers
- Backend developers
- MLOps and infrastructure teams
- Researchers serving open models
Pros and cons
- Open source with a broad set of documented features
- Works with many supported models and hardware platforms
- Integrates with popular AI frameworks and deployment tools
- Requires your own GPU, CPU, or TPU infrastructure and some technical setup
vLLM pricing
The vendor does not publish prices in a readable form (often pricing is shown only after signing in).
Is vLLM free?
Yes, there is a free plan. Free and open source; you pay only for your own compute.
vLLM alternatives
| Tool | Price from | Free plan | Category |
|---|---|---|---|
 Google AI Studio | 0,75 USD | ? | APIs & models |
 OpenAI Platform | 0,10 USD | ? | APIs & models |
 DeepInfra | 4.89 USD | ? | APIs & models |
 Cline | not listed | yes | APIs & models |
 OpenRouter | not listed | yes | APIs & models |
 Replicate | 0.025 USD | trial | APIs & models |
FAQ
What is vLLM used for?
Open-source inference and serving engine for large language models, for developers who need high-throughput LLM serving.
Is vLLM free?
Yes, there is a free plan. Free and open source; you pay only for your own compute.
How much does vLLM cost?
The vendor does not publish prices publicly or requires sign-in.
What are the best vLLM alternatives?
Closest alternatives: Google AI Studio, OpenAI Platform, DeepInfra, Cline, OpenRouter.
Data checked October 12, 2026 on the vendor website (docs.vllm.ai).