This module makes it possible to use mypy as part of a Python application. Since mypy still changes, the API was kept utterly simple and non-intrusive. It just mimics command line activation without starting a new interpreter. So the normal docs about the mypy command line apply. Changes in the command line version of mypy will be immediately usable. Just import this module and then call the 'run' function with a parameter of type List[str], containing what normally would have been the command line arguments to mypy. Function 'run' returns a Tuple[str, str, int], namely (<normal_report>, <error_report>, <exit_status>), in which <normal_report> is what mypy normally writes to sys.stdout, <error_report> is what mypy normally writes to sys.stderr and exit_status is the exit status mypy normally returns to the operating system. Any pretty formatting is left to the caller. The 'run_dmypy' function is similar, but instead mimics invocation of dmypy. Note that run_dmypy is not thread-safe and modifies sys.stdout and sys.stderr during its invocation. Note that these APIs don't support incremental generation of error messages. Trivial example of code using this module: import sys from mypy import api result = api.run(sys.argv[1:]) if result[0]: print(' Type checking report: ') print(result[0]) # stdout if result[1]: print(' Error report: ') print(result[1]) # stderr print(' Exit status:', result[2])