What are the limitations of distributing .pyc files?

I've started working on a commercial application in Python, and I'm weighing my options for how to distribute the application.

Aside from the obvious (distribute sources with an appropriate commercial license), I'm considering distributing just the .pyc files without their corresponding .py sources. But I'm not familiar enough with Python's compatibility guarantees to know if this is even workable, much less whether it's a good idea or not.

Are .pyc files independent of the underlying OS? For example, would a .pyc file generated on a 64-bit Linux machine work on a 32-bit Windows machine?

I've found that .pyc file should be compatible across bugfix releases, but what about major and minor releases? For example, would a file generated with Python 3.1.5 be compatible with Python 3.2.x? Or would a .pyc file generated with Python 2.7.3 be compatible with a Python 3.x release?

Edit:

Primarily, I may have to appease stakeholders who are uncomfortable distributing sources. Distributing .pyc's without sources may give them some level of comfort, since it would require the extra step of decompiling to get at the sources, even if that step is somewhat trivial. Just enough of a barrier to keep honest people honest.

Solution 1:

For example, would a file generated with Python 3.1.5 be compatible with Python 3.2.x?

No.

Or would a .pyc file generated with Python 2.7.3 be compatible with a Python 3.x release?

Doubly no.

I'm considering distributing just the .pyc files without their corresponding .py sources.

Python bytecode is high-level and trivially decompilable.

Solution 2:

You certainly could distribute the .pyc files only. As Cat mentioned, no it would not be compatible with different major version of Python. It might prevent some people from viewing the source code, but the .pyc files are very easy to decompile. Basically if you can compile it, you can decompile it.

You could use a binary packager like py2exe / py2app / freeze. I've never tried them but someone could still decompile them if they wanted to.