Blockify is described as 'TriBe productions proudly presents Blockify, a Spotify advert muter / blocker. Mutes only Spotify. Play your own MP3s during adverts. Control Spotify via keyboard hotkeys. Easy to use, totally portable. Unlike every other advert blocker, it doesn't rely on a list!' and is an app in the Web Browsers category. There are four alternatives to Blockify for Windows, Linux and Mac. The best alternative is EZBlocker, which is both free and Open Source. Other great apps like Blockify are Smutefy (Free, Open Source), Blockify (Free, Open Source) and Spotify Ad Blocker (Free, Open Source).
Smutefy is a small menu bar application that automatically detects and mute Spotify ads. How it works? Spotify uses growl to show a notification when a song changes. Smutefy uses growl log to detect ads and automatically changes the audio interface to mute the ad.
Portable - put it anywhere, run it and forget about it. (And you might want to enable "Run on startup" from the tray icon) Works by muting only Spotify during ads. The sound of your other applications will keep working.