CrossHair is an experimental tool and it runs your code. So, use it only with safe functions, don’t run it on the code that may wipe out your system or do bank transactions.

CrossHair is a third-party tool for finding bugs in Python code with deal support. It is a verifier-driven fuzzer (also known as “concolic testing”), something in between deal Tests and Formal verification. It calls the given function multiple times but instead of actual values it passes special mocks, allowing it explore different execution branches.


python3 -m pip install --user crosshair-tool


python3 -m crosshair watch ./examples/


CrossHair is a third-party tool. We’re not responsible for bugs in this integration. Use CrossHair issue tracker for all issues you encounter.

Further reading: