bookay is a set of free, open-source tools for self-hosting your bookmarks.

• a bookmarking service is useful if you use varying browsers or devices
• there is currently no free service that supports nested folders
• self-hosting your bookmarks offers the best privacy

• easily deployed backend
• customizable, keyboard-friendly browser plugin
• lightweight (~50 kB) web app
• support for nested folders
• data import and export
• scan for dupes and broken links
• support for multiple users per instance
• responsiveness and dark mode

You need to run a bookay server to use bookay. It includes the webapp by default and also feeds the browser plugin. There are a few free hosting solutions that suffice to run the server. See here for examples and deployment instructions.