Github doesn't make the distinction between OS or not. It's free if the repository is public, that is not the same thing as being open source.

The codeclimate link goes to a signup page, not an open source project information page.

jClarity says "So we offer a free license for use on your non-commercial Open Source projects". That's a interesting and hard to define restriction.

Lighthouse says "Create as many Open Source Projects as you wish on any plan". That's not saying there is a free plan for open source projects, there are no free plans in their case.