One example: Fossil (https://fossil-scm.org), the version control system used by SQLite itself. Fossil is Git-like in its underlying design but has a different interface. Fossil stores a complete source code repository as an SQLite database, rather than a pile-of-files as Git does. Storing content this way gives Fossil UI advantages over Git, such as the ability to easily find decedents of a check-in, and the ability to assign the same tag to multiple check-ins (ex: tagging every release with the "release" tag.)