DroxPerms is a Permissions Plug-in implementing the Bukkit Permissions-API. It supports Groups and Subgroups for easier Permissions-management and multiple worlds.

It also includes an API that allows external Plug-ins to

add Permissions to Players
remove Permissions from Players
change a Players Group
add Subgroups to Players
remove Subgroups from Players
add Information to a Players Info-node (like Prefix)
retrieve Information from a Players Info-node
add Permissions to Groups
remove Permissions from Groups
add Subgroups to Groups
remove Subgroups from Groups
add Information to a Groups Info-node (like Prefix)
retrieve Information from a Groups Info-node

To install DroxPerms simply put DroxPerms.jar into your plugins folder, default configs will be created on the first start. Information on how to use the commands and the file-structure can be found in the links below. If you use plugins that use the Permissions 2/3 API, then you might want to also put DroxPermsBridge.jar into plugins. DroxPermsBridge routes most of the Permissions 2/3 API to the DroxPerms API.

Wiki: https://github.com/hydrox/DroxPerms/wiki
Commands: https://github.com/hydrox/DroxPerms/wiki/Commands
Permissions: https://github.com/hydrox/DroxPerms/wiki/Permissions
File Formats: https://github.com/hydrox/DroxPerms/wiki/File-formats
API: https://github.com/hydrox/DroxPerms/wiki/API
Source-Code: https://github.com/hydrox/DroxPerms
Issue-Tracker: https://github.com/hydrox/DroxPerms/issues