If you want to contribute to the plugin API itself, you can check it out here. To make your own in-game plugins for XIVLauncher, check out the API documentation and the sample plugin. Please check this site for a list of them. XIVLauncher lets you use many community-created plugins that improve your game.
How can I improve my game with xivlauncher? Steps have been taken to ensure that it will always match retail, down to experiencing the same login issues. XIVLauncher has been designed to fully replicate the same login and authorization process as the official launcher. Is the XIV launcher the same as the official launcher? You can also use the /xlplugins command in chat. Open the system menu in-game by pressing escape, and then select 'Dalamud Plugins' from there. XIVLauncher supports the installation of plugins/addons made by third-party developers in-game. Frequently Asked Questions How to install third party addons in xivlauncher?