PyFlakes is described as 'A simple program which checks Python source files for errors' and is an app in the Development category. There are three alternatives to PyFlakes for Linux, Mac, Windows and Python. The best alternative is PyLint, which is both free and Open Source. Other great apps like PyFlakes are PyChecker (Free, Open Source) and flake8 (Free, Open Source).
Flake8 is a wrapper around PyFlakes, pep8 and Ned Batchelder's McCabe script and displays the warnings in a per-file, merged output. Flake8 also adds the ability to suppress warnings, additional source control hooks and is extendible.