Mypy is an optional static type checker for Python. You can add type hints to your Python programs, and use mypy to type check them statically. Find bugs in your programs without even running them! You can mix dynamic and static typing in your programs. You can always fall back to dynamic typing when static typing is not convenient, such as for legacy code.
Can be loaded as a module or used as a command-line tool for manual checking. Can be integrated with text editors or IDEs to operate automatically.