Schemathesis

Schemathesis automatically generates property-based tests from your OpenAPI or GraphQL schema and exercises 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.

Supported specifications

Specification	Versions
OpenAPI	2.0 (Swagger), 3.0, 3.1, 3.2
GraphQL	June 2018 and later

Why teams choose Schemathesis

• 🎯 Find real bugs on the first run (commonly 5–15 in production schemas).
• 🧠 Adapts as it runs: learns from server responses, threads real values into later requests, and shifts effort away from operations that aren't producing useful signal.
• ⏱️ No per-endpoint tests to maintain — point it at your schema and run.
• 🐛 Every finding ships with a minimal curl reproducer.
• 🔌 Plugs into existing setups: CLI, pytest, GitHub Actions, plus Allure, JUnit XML, and HAR output.

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

Important

Upgrading from older versions? See the Migration Guide for key changes.

Need help?

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