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Schemathesis is a modern API testing tool for web applications built with Open API and GraphQL specifications.

It reads the application schema and generates test cases, which will ensure that your application is compliant with its schema (read more about how it works in our research paper).

The application under test could be written in any language; the only thing you need is a valid API schema in a supported format.

Simple to use and yet powerful to uncover hard-to-find errors thanks to the property-based testing approach backed by state-of-the-art Hypothesis library.

🚀 Schemathesis is available as a service, standalone CLI, or a Python library 🚀

The service enables you to verify your API schema in a few clicks, CLI gives more control. has a free tier, so you can combine the CLI flexibility with rich visuals by uploading your test results there.

Signup to reveal all issues on a dashboard.


  • Content-Type, schema, and status code conformance checks for Open API;
  • Testing of explicit examples from the input schema;
  • Stateful testing via Open API links;
  • Concurrent test execution;
  • Targeted testing;
  • Storing and replaying network requests;
  • Built-in ASGI / WSGI application support;
  • Code samples for easy failure reproduction;
  • Ready-to-go Docker image;
  • Configurable with user-defined checks, string formats, hooks, and targets.

CLI installation

To install Schemathesis via pip run the following command:

pip install schemathesis

This command installs the schemathesis entrypoint + st as its alias.

You can also use our Docker image without installing Schemathesis as a Python package.


You can use Schemathesis in the command line directly (st is an alias to schemathesis):

st run --checks all

Or via Docker:

docker run schemathesis/schemathesis:stable \
    run --checks all

Or in your Python tests:

import schemathesis

schema = schemathesis.from_uri("")

def test_api(case):

CLI is simple to use and requires no coding; the in-code approach gives more flexibility.

Both examples above will run hundreds of requests against the API under test and report all found failures and inconsistencies along with instructions to reproduce them.

💡 See a complete working example project in the /example directory. 💡


Any contribution to development, testing, or any other area is highly appreciated and useful to the project. For guidance on how to contribute to Schemathesis, see the contributing guidelines.

Support this project

Hi, my name is Dmitry! I started this project during my work at I am grateful to them for all the support they provided to this project during its early days and for the opportunity to evolve Schemathesis independently.

In order to grow the community of contributors and users, and allow me to devote more time to this project, please donate today.

Also, I occasionally write posts about Schemathesis in my blog.


Additional content:

Non-English content:

  • A tutorial (RUS) about Schemathesis by @Stranger6667


The code in this project is licensed under MIT license. By contributing to Schemathesis, you agree that your contributions will be licensed under its MIT license.