Regarding plugin ID, do you guys know if there is any public database somewhere?
I know this page to register VST plugin IDs :
http://service.steinberg.de/databases/plugin.nsf/plugIn?openForm
was wondering if there is any au/aax equivalent?
I’m pretty sure it’s a combination of plugin id and manufacture code that makes the unique plugin key. I didnt register our plugins on the steinberg site anymore.
The registration site is totally outdated and no one knows how to find the page when you don’t have the direct link 
I don’t think there is something like this for AU and AAX.
1 Like
You have to register your company ID with Avid to make sure there are no conflicts.
Rail
With Apple, you can register a 4-character creator code for your company or other developer entity, e.g. -NI-, KORG, etc. Together with a 4-character code for your specific plugin and the plugin type this makes up the AudioUnit ID.
According to this discussion however, this seems to be no longer maintained:
https://forums.developer.apple.com/thread/38058