Can I Use Python 3? (GitHub), by Brett Cannon, is a tool to help you identify what is holding you back. It checks dependencies and find out which projects don’t have Python 3 support, here a few example output I ran:

$ caniusepython3 -p caniusepython3
Finding and checking dependencies ...

You have 0 projects blocking you from using Python 3!

$ caniusepython3 -p google-api-python-client
Finding and checking dependencies ...

You need 1 project to transition to Python 3.
Of that 1 project, 1 has no direct dependencies blocking its transition:

  google-api-python-client

$ caniusepython3 -p googlecl
Finding and checking dependencies ...

You need 2 projects to transition to Python 3.
Of those 2 projects, 1 has no direct dependencies blocking its transition:

  gdata (which is blocking googlecl)

There are three ways to check:

  1. requirements.txt,
  2. metadata PKG-INFO file of PEP 426, and
  3. comma-separated project IDs on PyPI, e.g. caniusepython3,pip.

The criterion of having Python support is:

As long as a trove classifier for some version of Python 3 is specified then the project is considered to support Python 3 […]

It seems this project is to created to bring more awareness of Python 3 availability, which I’d like to see more projects being ported to Python 3 from having this tool around.