It probably won't work great on things that spawn a separate process for sound. But it's worked fine on everything I've tried to use it on.
With browsers, it will adjust the volume of the most-recently played thing, which seems like correct behaviour to me.
It also has a second (less useful) mode of operation with two parameters. You can use it like:
`applicationvolume Spotify 50` (value can be relative or absolute in all cases).
The application name (`Spotify` in this case) is as-per the output of `pactl list sink-inputs | grep "application\.name"` (when audio is playing).
Linux Geeks doing what Linux Geeks do..