Ask HN: What license to use for my open source project?

The first step is to realize that #1 and #3 are incompatible.

By definition, "open source" means people who acquire the software, including those who download it from its github project page, are allowed to use it for commercial purposes without paying for a license.

You cannot say that a project is "open source" if it has a license which restricts it to non-commercial purposes.

This page by Github has pretty good outline of different Open Source license options: http://choosealicense.com/

It also pops up when you try to create a file named LICENSE* on the website.

I'd dual license it as GPL/Commercial. People can use GPL code for commercial purposes but its use will be limited, and any company serious about using it without risking legal issues will pay for the commercial version. Qt follows a similar model. You can look at AGPL if your project is SaaS.

I had trouble with this recently. I wanted something that prohibited hosted copies and forks but was free in other respects. I couldn't find anything.