Spotify Volume

You can conveniently control the Spotify volume from any page using Chrome. This is especially useful for controlling external speakers that play Spotify via Spotify Connect or Chromecast.

Disclaimer:
I want to clarify that I am not affiliated with or connected to the Spotify company. This is a small tool created independently, adding a feature I missed.
I've been using it for more than two years, and I decided to share the extension publicly, as I believe more people struggle with the same problem as I did.

PS. I usually listen to Spotify from my internet-connected soundbar, and creating an extension was the only way to easily control the playback volume besides catching the soundbar's remote control.