Pytype checks and infers types for your Python code - without requiring type annotations. Pytype can:

• Lint plain Python code, flagging common mistakes such as misspelled attribute names, incorrect function calls, and much more, even across file boundaries.
• Enforce user-provided type annotations. While annotations are optional for pytype, it will check and apply them where present.
• Generate type annotations in standalone files ("pyi files"), which can be merged back into the Python source with a provided merge-pyi tool.

Pytype is a static analyzer; it does not execute the code it runs on.

Thousands of projects at Google rely on pytype to keep their Python code well-typed and error-free.

For more information, check out the user guide, FAQ, or supported features.

Atheris is a coverage-guided Python fuzzing engine. It supports fuzzing of Python code, but also native extensions written for CPython. Atheris is based off of libFuzzer. When fuzzing native code, Atheris can be used in combination with Address Sanitizer or Undefined Behavior Sanitizer to catch extra bugs.