ZFIN has multiple levels of versioning:
Database
The database is backed up nightly, producing a time stamped archive that can be retrieved back to 2007. The backups are Postgres dump files (back to 2018 while prior to 2018 back files are store for an Informix database) that can easily be loaded into a new Postgres / Informix instance.
Software
In addition to database backup files, ZFIN versions the software by release name: release-<ID>. The software lives in GitHub.
Download Files
ZFIN also provides download files (user facing) that are generated nightly. They are time stamped back to 2012.