The current version is 4.0.1. This was a major rework in order to continue to support the latest Mac OS. It will require some migration if you upgrade from anything earlier than 4.0. The previous version before the rework can be found here: version 3.0.1 in case you do not want to go through the migration.
Please read the known issues page and backup your data frequently while using this or any database program!
(all Operating Systems)