Primer

Primer is a free virtual synthesizer available for macOS, Windows, and iPad in AU, VST, and VST3 formats. It integrates with the Syntorial learning platform, but you can use it for free even if you don’t own Syntorial. Primer is perfect for learning synthesis. Its interface is optimized for beginners, and like Charlatan, I recommend it to anyone who wants to learn how to program a synth from scratch. One of the coolest features is the Famous Sounds Preset Library, which recreates iconic synth sounds from popular tracks.

It’s a great way to reverse-engineer sounds you’ve heard and understand how they were made. The plugin features a clear subtractive synthesis layout with three oscillators, multiple filter types, modulation envelopes, LFOs, and voice modes. Built-in effects include ring modulation, distortion, phaser, chorus, delay, and reverb. Even if you’re not new to synthesis, Primer is a great lightweight synth compared to workhorses like Vital or Surge XT.