MusicButler dev here. Even though you didn't sign up for the paid plan, I appreciate the mention and the compliments!
And to /u/bartproost - good luck with your new adventure! Your note on monetization reminds of myself 4 years ago when I'd just started with MusicButler. Luckily I didn't make any promises about it being free forever because, well, hobby projects have associated costs too.
I was curious about the service (I'm not against paying for stuff and MusicButler supports Apple Music) but nowhere on the website does it tell me how much it costs.
Music Butler focuses on either artists you follow on Spotify (just like Spotify itself), or your Spotify Library. Brew.fm shows you new releases per playlist.
I have no plans to monetize the tool. I'm scratching my own itch here and am very much at the mercy of Spotify. I'm hoping to keep this one a hobby project.
I did find the service very useful for the 3ish years I used it, but I didn't jump to premium, and kinda stopped using it.
Curiously, what makes this service different and how will you ensure "100% perpetually free with no strings attached"?
https://www.musicbutler.io/