Learn how to create a modern API service using FastAPI’s powerful features. This guide shows you how to publish a Python-based API with automatic scaling.

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What you’ll learn

FastAPI

Build modern Python APIs

Autoscaling

Publish with automatic scaling

Performance

Create high-performance endpoints

Documentation

Auto-generate API docs

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Create your API

1

Fork the template

Sign in to Replit and fork the FastAPI template. Select + Use Template and follow the prompts to create your Replit App.
FastAPI automatically generates interactive API documentation at /docs.
2

Set up publishing

  1. Select Publish in the workspace header
  2. Choose Autoscale deployment
  3. Configure your API:
    • Machine: 1vCPU, 2 GiB RAM (default)
    • Max machines: 3 (default)
    • Run command: uvicorn main:app --host 0.0.0.0
Autoscale deployments automatically adjust resources based on API traffic.
3

Launch

Select Publish to launch your API. It will be live in a few minutes!

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Customization options

Endpoints

  • Add new routes
  • Implement validation
  • Handle authentication

Documentation

  • Customize API docs
  • Add examples
  • Define schemas

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Next steps

Custom Domain

Add your own domain

Databases

Add data persistent storage

Monitoring

Track performance

Create a Flask app

Build with Flask

Build with AI

Create apps using Agent
Want to learn more about API development? Check out our publishing documentation.