pycodestyle is a tool to check your Python code against some of the style conventions in PEP 8.

• Plugin architecture: Adding new checks is easy.
• Parseable output: Jump to error location in your editor.
• Small: Just one Python file, requires only stdlib. You can use just the pycodestyle.py file for this purpose.
• Comes with a comprehensive test suite.

You can install, upgrade, uninstall pycodestyle.py with these commands:

$ pip install pycodestyle
$ pip install --upgrade pycodestyle
$ pip uninstall pycodestyle

There's also a package for Debian/Ubuntu, but it's not always the latest version.

$ pycodestyle --first optparse.py
optparse.py:69:11: E401 multiple imports on one line
optparse.py:77:1: E302 expected 2 blank lines, found 1
optparse.py:88:5: E301 expected 1 blank line, found 0
optparse.py:222:34: W602 deprecated form of raising exception
optparse.py:347:31: E211 whitespace before '('
optparse.py:357:17: E201 whitespace after '{'
optparse.py:472:29: E221 multiple spaces before operator
optparse.py:544:21: W601 .has_key() is deprecated, use 'in'

You can also make pycodestyle.py show the source code for each error, and even the relevant text from PEP 8:

$ pycodestyle --show-source --show-pep8 testsuite/E40.py
testsuite/E40.py:2:10: E401 multiple imports on one line
import os, sys
         ^
    Imports should usually be on separate lines.

    Okay: import os\nimport sys
    E401: import sys, os

Or you can display how often each error was found:

$ pycodestyle --statistics -qq Python-2.5/Lib
232     E201 whitespace after '['
599     E202 whitespace before ')'
631     E203 whitespace before ','
842     E211 whitespace before '('
2531    E221 multiple spaces before operator
4473    E301 expected 1 blank line, found 0
4006    E302 expected 2 blank lines, found 1
165     E303 too many blank lines (4)
325     E401 multiple imports on one line
3615    E501 line too long (82 characters)
612     W601 .has_key() is deprecated, use 'in'
1188    W602 deprecated form of raising exception

• Read the documentation
• Fork me on GitHub