Every plugin you install comes in a format, and the format decides which DAW can load it and what the DAW can do with it. Most producers never think about it until a download page offers three files and one of them says CLAP. Here is what the three desktop formats actually are, what changes between them, and which one to pick.
VST3: the one almost everything loads
VST3 is Steinberg's format. VST goes back to 1996, and VST3 replaced the old VST2 in 2008. Today it is the default on Windows and the common ground on macOS: Cubase, Ableton Live, FL Studio, Bitwig, REAPER and Studio One all load it. Logic Pro and GarageBand do not.
What VST3 gives you over the old format: sample accurate automation, sidechain inputs that the host understands, processing that can go idle when the plugin is silent, and note expression for hosts that support it. Steinberg owns the specification and licenses the SDK, which is why the format evolves at Steinberg's pace.
AU: Apple's format, and the only one Logic speaks
Audio Units is built into macOS. If you work in Logic Pro, GarageBand or MainStage, AU is not a choice, it is the only door. Most other Mac DAWs load AU too, so on a Mac you often have both AU and VST3 of the same plugin installed.
Apple validates AU plugins with a tool called auval, and a plugin that fails validation simply will not show up in Logic. That strictness is annoying for developers and good for you. There is no Windows version of AU.
CLAP: the new one, built by plugin people
CLAP stands for CLever Audio Plugin. Bitwig and u-he released it in 2022 and put it under the MIT license, which means anyone can implement it without a contract, a fee or permission. That alone is a big deal for small developers like us.
The technical differences are the interesting part:
- Per note modulation. A CLAP host can modulate a parameter on one note while the other notes keep their own value. Think of it as MPE for every parameter, not just pitch, pressure and timbre.
- Modulation is separate from automation. In VST3, an LFO in your DAW moving a knob overwrites the knob. In CLAP, modulation is an offset on top of the value you set, so your setting is still there when the modulation stops.
- Host managed threading. The DAW can tell the plugin how many cores it may use, so heavy plugins and the host stop fighting over the CPU.
- Extensible by design. New features are added as optional extensions. Old hosts ignore what they do not understand instead of breaking.
Hosts that load CLAP today: Bitwig, REAPER, FL Studio from 21.2, Studio One from 6.5, and a handful of smaller ones. Not yet: Logic, Ableton Live, Cubase, Pro Tools.
So which one should you install?
- Logic, GarageBand, MainStage: AU. Nothing else loads.
- Cubase, Nuendo: VST3.
- Ableton Live: VST3 on Windows. On a Mac either works; pick one and stay with it so your sessions stay consistent.
- Bitwig, REAPER, FL Studio 21.2 and later, Studio One 6.5 and later: CLAP if the plugin offers it, VST3 otherwise. You lose nothing, and you gain the modulation behavior above as developers start using it.
- Pro Tools: AAX only, which is a separate format with its own licensing.
One warning that applies to every format: a session remembers which format of a plugin it used. If you open a project built with the VST3 and only the CLAP is installed, the track comes up empty. Keep the format you started with installed, even if you switch for new work.
Where CustomTone 2 stands
CustomTone 2 ships as VST3 and AU, and from version 1.0.7, rolling out now, as CLAP on both macOS and Windows. All three come from the same engine, so presets, sessions and your sign in are shared. The CLAP build exposes the automatable parameters, which makes the list in your DAW shorter and cleaner than the VST3 one. Per note modulation of the Multi-Key engine is the obvious next step for us, and CLAP is the format that makes it possible.
If you own CustomTone 2, the installer already puts the CLAP in place. If you do not, it is here.
