[stephencanon]

Writing software, in and of itself, does no more to advance science than building houses does to advance structural engineering.

If they are specifically writing software to be used for scientific research, or are carrying out significant research into computing and releasing papers/patents freely, then they might qualify.

[Karunamon]

So let's look at some of the existing ones like Wikimedia or Apache. What are they doing to claim that particular exemption?

[DougBTX]

Here's Wikimedia's confirmation of exemption letter.

https://upload.wikimedia.org/wikipedia/foundation/9/90/501%2...

To go further, I'd look up exactly what "Public Charity Status 170(b)(1)(A)(vi)" is, and then compare that to how they describe themselves here: https://wikimediafoundation.org/wiki/FAQ/en

[kijin]

In a different thread a couple of days ago, someone mentioned that Apache got a scientific exemption.

Which is not surprising at all, since the Apache HTTP Server had its roots in the National Center for Supercomputing Applications (NCSA), a scientific institution.

Python Software Foundation also got a scientific and educational exemption.

[stephencanon]

I expect that they aren't claiming a scientific purpose. More likely they claim to be educational, or that they provide a public work.

[lacksconfidence]

at least in the case of wikimedia, software is merely a byproduct of their goal. To quote their main page:

    Wikimedia is a global movement whose mission is to bring free educational content to the world.