To make it easier to find and compare libraries that solve similar, common problems we maintain a catalog of categories.
The catalog itself is maintained via plain YAML files on GitHub. If you'd like to add a library to a category please file a Pull Request there.
Both Rubygems as well as direct references to GitHub repositories are possible. If your library is packaged as a Rubygem please always prefer to reference the Rubygem and make sure you have referenced your GitHub repository in the gemspec.