# Chainlit — Build Conversational AI Apps Fast

> Python framework for building production conversational AI interfaces in minutes. Chat UI, streaming, file upload, feedback, auth, and LangChain/LlamaIndex integration. 12K+ stars.

## Install

Save as a script file and run:

## Quick Use

```bash
pip install chainlit
```

```python
# app.py
import chainlit as cl

@cl.on_message
async def main(message: cl.Message):
    response = f"You said: {message.content}"
    await cl.Message(content=response).send()
```

```bash
chainlit run app.py
```

Open `http://localhost:8000` — you have a chat UI.

---

## Intro

Chainlit is a Python framework for building production conversational AI interfaces in minutes. It provides a polished chat UI with streaming, file upload, feedback collection, authentication, and data persistence — out of the box. Integrates natively with LangChain, LlamaIndex, Haystack, and any Python LLM library. 12,000+ GitHub stars, Apache 2.0.

**Best for**: Python developers who need a chat interface for their AI app without building frontend
**Works with**: OpenAI, Anthropic, LangChain, LlamaIndex, Haystack, any Python LLM library

---

## Key Features

### Instant Chat UI
Beautiful, responsive chat interface with zero frontend code. Streaming, markdown, code highlighting, and LaTeX.

### File Upload & Display
Users can upload files. Agents can send images, PDFs, and data visualizations.

### Feedback & Human Evaluation
Built-in thumbs up/down feedback on AI responses. Export for fine-tuning.

### Multi-Step Display
Show intermediate "thinking" steps, tool calls, and chain-of-thought reasoning.

### Authentication
Built-in auth with OAuth (Google, GitHub) or custom login.

### Data Persistence
Conversation history saved automatically. Resume sessions across visits.

### Framework Integration
```python
# LangChain integration
@cl.on_message
async def main(message):
    result = await chain.ainvoke({"input": message.content},
        callbacks=[cl.LangchainCallbackHandler()])
    await cl.Message(content=result).send()
```

---

### FAQ

**Q: What is Chainlit?**
A: A Python framework for building conversational AI interfaces in minutes — chat UI, streaming, file upload, feedback, and auth included. 12K+ stars.

**Q: How is Chainlit different from Streamlit?**
A: Chainlit is purpose-built for chat/conversational AI with streaming, multi-step display, and LLM framework integrations. Streamlit is a general data app framework.

---

## Source & Thanks

> Created by [Chainlit](https://github.com/Chainlit). Licensed under Apache 2.0.
> [Chainlit/chainlit](https://github.com/Chainlit/chainlit) — 12,000+ GitHub stars

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Source: https://tokrepo.com/en/workflows/bf4ae5cd-e9e7-4a7d-a6d5-4c7e51d5e957
Author: Script Depot