Support for UUIDs as of version 1.21
YAML backend, with new, fully rethinked, config schema. Now all user, groups and their permissions are stored in one file - permission.yml. File name can also be adjusted.
SQL backend, most delicious. Currently MySQL and SQLite supported, but other DB (like Postgre) are possible too. PEX deploys the DB scheme (tables and initial data) automatically. This means, that you only need to provide data on how to connect to the db, everything else PEX will handle by itself.
Flexible architecture and API - you can change a lot programmatically.
Rich chat/console command interface. You can do almost everything ingame. Command list below.
Modifyworld - Permission-based restrictions mechanism (we call it "modifyworld"), which provides the possibility to control players abilities, such as destroying/placing blocks, riding carts/boats or even getting spotted by mobs and much more. Available from its project page
Multigroup inheritance. User, as well as Group, can be member of several groups. And inherit their permissions, options and prefix/suffix.
Permissions based upon Regular Expressions. This mean you can use regular expressions. Example: modifyworld.blocks.(destroy|place).(3|12) - this permission allow place or destroy only sand (12) or dirt (3) blocks. There is still limitation on dot usage in your regexps - dots are escaped by default. Raw regex flag is also available and explained on the wiki.
Multiworld permissions. Just don't specify world and permission would work in any world.
Multiworld inheritance. You can inherit different groups in different worlds.
Perfomance friendly. Low-level caching helps a lot when you have 100+ online users
Promotional/Demotional system. You can assign ranks to groups and promote/demote users to higher/lower ranked group. NEW: new you can make serveral ranking ladders.
World-inheritance - permissions/option of one world can be inherited by another world.
Timed Permissions - you can give user permission only for some amount of time.
As of version 1.21.1, PermissionsEx automatically updates to keep you up to date with the latest bugfixes and new features. The automatic update functionality will only perform updates between minor releases (for example only 1.21.1->1.21.2, not 1.21.3->1.22). To disable it, set the updater option to false in plugins/PermissionsEx/config.yml.
Bukkit Permissions (SuperPerms) compatible.

KFG_Ranks