Best Free Virtual Synth Plugins for Mac (AU) in 2025
Synthesizers are at the heart of modern music production — from electronic and ambient to pop, soundtracks, and experimental genres. For Mac users working with AU (Audio Unit) plugins, the good news is that there’s a growing collection of powerful free synth plugins that deliver excellent sound quality, flexibility, and creative potential.
If you’re building a synth-based setup or just looking to expand your palette, here’s a comprehensive guide to the best free AU synth plugins available in 2025.
1. Surge XT
A powerhouse among open-source synthesizers. Surge XT combines subtractive, FM, wavetable, and physical modeling synthesis with a flexible modulation system.
AU-compatible
Rich factory presets, scalable UI, extremely stable
Great for: hybrid textures, advanced sound design
2. Helm – by Matt Tytel
A semi-modular soft synth with intuitive routing and a polished interface. Helm is light on CPU and surprisingly deep, with plenty of modulation and customization options.
AU and standalone
Great for: basses, leads, evolving pads
3. Dexed
An accurate emulation of the Yamaha DX7, capable of loading original .SYX patches. While the interface takes some time to learn, it’s a classic FM beast.
AU compatible
Great for: retro sounds, bell tones, FM pads
4. Full Bucket Music Synths
This developer offers a rich lineup of classic emulations:
• FB-3100 (Korg PS-3100)
• The Blooo (analog-style subtractive synth)
• ModulAir (modular architecture)
• Tricent (Korg Trident-inspired)
AU for macOS
Great for: analog warmth, vintage emulation, modular patching
5. Cardinal (based on VCV Rack)
A fully modular synth environment, self-contained and perfect for DAW use. You get the freedom of Eurorack in a free AU plugin.
AU-compatible version
Great for: modular experimentation, generative synthesis, sound design
6. Zebralette – by u-he
An intro to Zebra’s engine, Zebralette is a wavetable synth that surprises with depth and clarity. Ideal for melodic lines and atmospheric layers.
AU
Great for: cinematic leads, gentle arps, pads
7. Podolski – by u-he
Simple but charming, Podolski has one oscillator, one filter, and one envelope — but its musicality and ease of use make it ideal for sketching ideas.
AU
Great for: synth-pop, sequences, melodic sketches
8. Tyrell N6 – by u-he
Inspired by classic Roland analog synths, Tyrell N6 offers a thick, warm analog sound with plenty of tweakability.
AU
Great for: Juno-style chords, creamy leads, vintage synth sounds
9. TAL NoiseMaker
One of the most loved free synths for years, TAL NoiseMaker is flexible, gritty when needed, and has a clean GUI.
AU
Great for: electronic genres, gritty basslines, distorted pads
10. Odin 2
A powerful free synth with multiple oscillator types (FM, wavetable, vector), flexible routing, and excellent sound. AU support
Great for: hybrid synthesis, scoring, complex sound layering
11. Synth1
A legendary synth inspired by the Nord Lead 2, Synth1 is incredibly lightweight and reliable.
AU version available through third-party ports
Great for: electronic music, simple patches, leads and bass
How to Choose the Right Synth for You
Need analog emulation? Try Tyrell N6 or FB-3100
Into FM or digital tones? Dexed or Odin 2 are excellent
Want modular freedom? Go with Cardinal or ModulAir
Prefer fast results? Podolski, TAL NoiseMaker or Zebralette keep things simple
Explore More with ONE Instrument
If managing all your synths and sounds feels overwhelming, ONE Instrument offers a cleaner way forward.
This free Audio Unit plugin for Mac lets you scan, preview, and organize your entire collection of virtual instruments — including synths — inside one unified interface. You can layer multiple plugins, tweak parameters, and even record your ideas instantly with the built-in recorder.
What sets it apart is the curated selection of free synth instruments chosen by musicians, ready to play without digging through endless downloads.
If you’re building your sound on Mac, ONE Instrument is the place to bring it all together — freely and creatively.