This was asked in the Robot Framework’s RoboCon conference one year. Yes many OSS projects have tasks for and want testers, document reviewers & other roles outside of just dev. Simply contact a specific project team + I’m sure they’ll be glad to help you get started... 

There are many ways you can contribute to open source projects as a tester.

@alex_read mentioned some of those already, I’d like to add these:

• Improve coverage of tests for the project
• Write blog posts or record video tutorials on how to get started using the project
• Create artwork for documentation, icons, etc.

I would definitely say that most open source tool repositories not dev-only repositories.

As the developer of RestAssured.Net I’d love to tell you more about how to contribute to it.

I’m all ears @basdijkstra ! Sent you a DM