Schemathesis

Catch API bugs before your users do.

Schemathesis automatically generates thousands of test cases from your OpenAPI or GraphQL schema and finds the edge cases that break your API.

Finding a server error that manual testing missed

Find Bugs in Your API in 5 Minutes

Try it now

uvx schemathesis run https://example.schemathesis.io/openapi.json

This command will immediately find real bugs in a demo API and show you exactly how to reproduce them.

Bugs Schemathesis finds cause real problems:

• Registration forms that crash on legitimate international names
• Shopping carts accepting negative quantities or invalid product IDs
• User profiles returning incomplete data that breaks mobile apps

Why developers choose Schemathesis

Immediate results:

• 🎯 Find 5-15 real bugs in a typical API within the first test run

• ⏱️ 1-minute setup - Just point it at your OpenAPI schema

• 🔄 Zero maintenance - Automatically tests new endpoints as you add them

Easy integration:

• 🔌 Works with existing tools - Supports variety of export formats like JUnit and HAR

• 📑 Uses your existing docs - Reads OpenAPI/GraphQL schemas you already have

• 🐍 Has a flexible Python API - Integrates with pytest directly

Developer feedback

"The tool is amazing as it can test negative scenarios instead of me and much faster!"

— Luděk Nový, JetBrains

Documentation

• New to Schemathesis?

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  Get started in minutes:

  • Quick Start - 5 minutes
  • CLI Tutorial - 20 minutes
  • Pytest Tutorial - 15 minutes

• How-To Guides

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  Practical guides for common scenarios:

  • CI/CD Integration
  • Extending Schemathesis
  • More...

• Want to understand how it works?

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  Deep dive into concepts:

  • Data Generation
  • Example Testing
  • Stateful Testing

• Need technical details?

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  Complete reference:

  • Command-Line Interface
  • Python API
  • Configuration File

Need help?

• Resources — Community articles, videos, and tutorials
• FAQ — Frequently Asked Questions