Provide an AWS unique ID (e.g. beginning with AIDA… or AROA…) and hit "Go". The principal ARN will be looked up using this process. Need a sample ID? Try AROAXWYRR55VD5K5I7HZX.
You can also run this from the terminal: curl awsid.dev.ak2.au/id/AROAXWYRR55VD5K5I7HZX
Hacked together by Aidan Steele. See the caveat on GitHub about data collected by this service.