FastChat
Inference & Compute · Free + paid
Distributed multi-model LLM serving system with OpenAI-compatible API and web UI
At a glance
- Made by
- LMSYS
- API
- Yes
- Available on
- Web, CLI, API
- Open source
- Apache-2.0
- GitHub
- 39,549 stars · Apache-2.0
What is FastChat?
FastChat is an open platform for training, serving, and evaluating LLM-based chatbots. Its core features include training and evaluation code for models such as Vicuna and MT-Bench, and a distributed multi-model serving system with a web UI and an OpenAI-compatible RESTful API. It says it powers Chatbot Arena and has handled more than 10 million chat requests across over 70 LLMs. You can install it with pip or from source and chat with models from the command line.
- Training and evaluation code for Vicuna, MT-Bench, and more
- Distributed multi-model serving with a web UI and an OpenAI-compatible RESTful API
- Command-line (CLI) inference
- Web GUI serving
- Fine-tuning
- Powers Chatbot Arena
Who uses FastChat and for what
- Running a service like Chatbot Arena that compares multiple LLMs side by side
- Chatbot model training and MT-Bench evaluation
Pricing
Usage-based pay-as-you-go (cloud/GPU)
Pay-as-you-go based on GPU/inference time or API call volume, some open-source self-hosting options available
Estimate based on AI knowledge - please verify on the official site
AI tools similar to FastChat (alternatives)
FastChat vs. alternatives at a glance
| AI | Pricing | Combos on the map | Connected tools | Free | Cheapest monthly | Korean |
|---|---|---|---|---|---|---|
| FastChat | Free + paid | 0 | 6 | — | — | — |
| EXO | Free | 0 | 6 | — | — | No |
| LM Studio | Free + paid | 0 | 6 | Yes | $20/mo | No |
| ollama | Free + paid | 0 | 6 | Yes | $20/mo | — |
| Open WebUI | Free + paid | 0 | 5 | — | — | No |
2 of these 5 tools have a free plan. Cheapest paid plan: LM Studio ($20/mo).
Combo and connection counts are based on the relationships recorded on AI Galaxy Map (2026-10-26); they are not a quality ranking.
FastChat on AI Galaxy Map
- One of 43 AI tools in the Inference & Compute field.
- Connected to 6 other tools — #6 in its field.
Frequently asked questions
Can I use FastChat for free?
Usage-based pay-as-you-go (cloud/GPU). Prices can change, so check the official site before paying.
What AI can I use instead of FastChat?
Tools that do the same job, such as EXO, LM Studio, ollama, Open WebUI, are connected to it on the map.
Sources (official pages)
Checked on the official pages on 2026-10-14. Prices and features can change, so check the official site again before paying.