This app offers the quickest way to figure out which earbud is right and which is left.
Connect your headphones, open the app and click.
If that is not fast enough, you can use the home screen widget for even faster use.

Our promises:
No need to grant any special permissions.
This app does not and will not (ever) use ads.
It's free, it's small, it's meant for one thing and it does it well.