Ask HN: How are open source developers making money?

More often than not by working a full-time job somewhere else.

Besides that, there are support contracts, sponsorships and stuff like that, but I'd say there are not a lot of people able to live from that alone.

Donations, documentation books/ebooks, small jobs modifying code as a consultant.

Open Source and Free Software have an NPR/PBS business model sometimes corporations like Microsoft and IBM donate to them, sometimes they have to take donations from users.

Lots of resources for that here:

https://github.com/fossjobs/fossjobs/wiki/Resources

Support contracts.