gitmark is a dead simple bookmarking browser extension that saves bookmarks to a GitHub repository.
Currently, only Firefox with GitHub is supported. Please contribute if you want more platforms and providers supported!
You can download the Firefox extensions from the release page here.
To use gitmark, you need a GitHub account, and a personal access token. Once you have those, plug your username and token in here. Then go ahead and click "initialize" - that will create a new repository on GitHub for you which will be used to store your bookmarks. Now all you need to do is browse around until you find a website you like, click the button in your browser toolbar and hit "add".