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.
Thanks for your comments. I'll update Code Climate link.
Yes, saying that Github, jClarify and Lighthouse have free for open source plans is technically incorrect. But given that they can all* be used by open source projects, for free, in ways that they could not be used by typical commercial projects I think the simplification is permissible.
* Lighthouse do have a free plan. "Create as many Open Source Projects as you wish on any plan! Even the free plan!"
To add to your devtools list as you asked in your article :
OAuth.io "OAuth-as-a-service" is also free for open source projects, by using directly the open source daemon oauthd for 80+ providers https://github.com/oauth-io/oauthd
Travis CI is as free for Open Source as Github is; Notably, it also makes some of the other tools even sweeter (Like Code Climate, Sauce Labs, Github itself).
It's a little bit ironic that we can't alter the blog post about open source directly through comments, and instead have been asked to use Hacker News.
Moqups[1], our HTML5 based mockup/wireframing app, is completely free for education, non profit and open source projects. To our great surprise, we get a fairly large amount of requests each week from many universities and from open source developers. Aaaand we're happy to fulfill all of them :-)
You also forgot LiveCode, a RAD application that uses a variant of AppleScript to do quick UI and function prototyping for cross-platform open-source applications.
Excelsior JET (http://www.excelsiorjet.com), a Java SE JVM with a native code compiler and deployment toolkit, is free for non-commercial use. Note that "non-commercial" != "open source", both ways: there is commercial open-source and closed-source freeware.
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.