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FastAPI AI Chat with WebSocket

A real-time AI chat application using Next.js, FastAPI, WebSocket, and the Python AI SDK.

DeployView Demo

FastAPI AI Chat with WebSocket

A real-time AI chat application using Next.js (frontend), FastAPI (backend), WebSocket for streaming, and the Python AI SDK for LLM integration. Deployed on Vercel using Services.

Demo

https://fastapi-ai-chat.vercel.app/

How It Works

  • The frontend is a Next.js single-page app with a chat UI that connects to the backend via WebSocket.
  • The backend is a FastAPI server that accepts WebSocket connections, streams LLM responses using the Python AI SDK, and sends text deltas back to the client in real time.
  • On Vercel, the frontend and backend run as separate services routed by path prefix (/ and /api).

How to Use

Local Development

# Clone
npx giget@latest gh:vercel/examples/websockets/fastapi-ai-chat fastapi-ai-chat
cd fastapi-ai-chat


# Set your AI Gateway API key
echo "AI_GATEWAY_API_KEY=your-key-here" > .env


# Run both services
vercel dev

Open http://localhost:3000.

Environment Variables

VariableDescription
AI_GATEWAY_API_KEYVercel AI Gateway API key (required)
AI_MODELModel to use
(default: anthropic/claude-sonnet-4-6)

Learn More

  • Vercel Services - learn how services work on Vercel.
  • AI Gateway - learn about AI Gateway.
GitHub
Ownervercel
Repositoryexamples
LicenseView License
Use Cases
Starter
AI
Stack
Next.js
FastAPI
DeployView Demo