Chainlit
Production-ready chat UIs for LLM apps in pure Python — no frontend code needed.
About
Chainlit is an open-source async Python framework for building conversational AI applications with production-ready chat interfaces. Decorate Python functions with handlers like @cl.on_message and Chainlit provides a ChatGPT-like UI with real-time streaming, multimodal support (text, images, files, audio), authentication, and data persistence — all without writing HTML, CSS, or JavaScript. It integrates with LangChain, LlamaIndex, OpenAI, and Anthropic, and supports embedded chatbots, custom frontends, and API endpoints.
The honest caveats: it is a presentation layer, not a chatbot engine — you still bring your own LLM logic. The out-of-the-box UI is chat-shaped, so heavily custom designs need frontend work. Built by the Literal AI team, the project is solid for prototypes and internal tools, but compare with Streamlit or Gradio if your app is not chat-first.
What it can do
- ChatGPT-like chat UI from Python decorators
- Real-time response streaming
- Multimodal messages and file uploads
- Built-in authentication options
- Deployable to web, Slack, Discord, Teams
Setup
pip install chainlit, then run chainlit run app.py to launch your chat app.
Prerequisites
Python 3.9+; an LLM provider API key for your chosen model.
Use cases
Works with
Trust score — 8/10
Scored 8/10 (verified tier, metrics-v1). Evidence: Verified via vendor site/docs/GitHub and reputable coverage, wave 85; Trending score 84/100 from researcher assessment.
Sources
Every fact above was checked against these sources. Where a claim comes from the provider and couldn't be independently verified, the text says so.