Creating an Extensions Repository
Third party sites that wish to support extensions in Blender can do so in several ways, in order of complexity:
Static: Host a static JSON file listing all the packages of your repository.
Dynamic: Serve the JSON file on-demand based on the Blender version and platform.
Platform: Fork the entire Extensions Website to create your own.
Tags and Translations
If you are planning to use a different set of tags than the ones used by Blender Extensions Platform, remember to submit a pull request to tags.py.
This way they can be shown translated within Blender.