While working on a project, you wrote a utility to solve a problem. Then you started using it in other projects. It looks like the code you wrote is very useful, and other people might benefit from it, so you decided to publish it on GitHub. What should you do? In this talk, we will discuss the benefits of Open Source, work with the community, choose a license, API design and developer experience, the importance of writing test, and how to write proper documentation. You cannot miss any of those if you want your library to be successful, and if it does, you will be a maintainer. And now?