VST2 vs VST3 vs AU vs AAX: What’s the Difference and What Should You Use?

If you’ve ever downloaded a plugin and been asked to choose between VST2, VST3, AU, or AAX, you’re not alone. For many producers, that installer screen is where confusion starts.

The good news is this: plugin formats aren’t something you need to obsess over. They matter only at install time, and once you know which one your DAW prefers, the decision becomes automatic.

This guide explains what each format is, when to use it, and what actually matters for your setup – without getting technical or overcomplicated.

Plugin Formats Explained

Plugin formats are simply standards that allow plugins to run inside a DAW. Think of them as different “languages” your DAW understands.

Some DAWs speak only one language, while others support several. The plugin format doesn’t change how a plugin sounds – it affects compatibility, performance, and how the plugin integrates with your DAW (If you want a broader understanding of plugins in general, start with our guide on what VST plugins are).

So if you’re wondering what the difference is between all these plugin formats – here’s a quick overview:

Format	Works On	Commonly Used By	When to Use It
VST2	Windows, macOS	Older DAWs, legacy setups	Only if VST3 isn’t available
VST3	Windows, macOS	Most modern DAWs	Best choice for most producers
AU	macOS only	Logic Pro, GarageBand	Required for Logic Pro
AAX	Windows, macOS	Pro Tools	Only if you use Pro Tools

In short, VST3 is the format most producers should be using. To understand why, we’ll take a closer look at each format below.

VST2 (The Legacy Format)

VST2 is the original plugin format created by Steinberg. For many years, it was the industry standard, which is why a large number of older plugins (and some free ones) still offer VST2 versions today.

This format works on both Windows and macOS and is still supported by many DAWs. That said, the format has largely been replaced by VST3 and doesn’t take full advantage of modern DAW features. Compared to newer formats, VST2 is less efficient when it comes to CPU handling and deeper integration.

Today, VST2 mainly exists for backward compatibility. It’s still useful when a plugin doesn’t offer a VST3 version, but for most modern setups, it’s no longer the preferred choice.

VST3 (The Modern Default)

VST3 is the updated version of VST2 and the format most developers actively support today. It was designed specifically to improve performance, workflow, and how plugins interact with modern DAWs.

One of the biggest advantages of VST3 is more efficient CPU handling. Many producers notice better multithreading behavior, with workloads spread more evenly across CPU cores – especially in DAWs like Reaper, Ableton Live, and Cubase. VST3 also provides cleaner automation, proper sidechain support, and more reliable parameter handling overall.

For most producers, VST3 is the most practical and future-proof option. If your DAW supports it, this is usually the format you’ll want to install.

AU (Apple’s Plugin Format)

AU (Audio Units) is Apple’s native plugin format and works exclusively on macOS. It’s tightly integrated with Apple’s ecosystem and is the only plugin format supported by Logic Pro.

For Logic Pro users, AU isn’t optional – it’s required. GarageBand also relies on AU plugins, making this format essential for many Mac-based producers. Other macOS DAWs may support both AU and VST3, but outside of Logic, there’s rarely a clear advantage to choosing AU over VST3.

AAX (Pro Tools Only)

AAX is Avid’s proprietary plugin format designed exclusively for Pro Tools. It exists to support Pro Tools’ specific architecture and workflow, including both Native and DSP-based systems.

Because AAX is limited to Pro Tools, it isn’t relevant for producers using other DAWs. AAX plugins also tend to come with larger install sizes, which can matter if storage space is limited. If you don’t work in Pro Tools, installing AAX plugins won’t provide any benefit, and they won’t appear in other DAWs anyway.

Common Plugin Installation Mistakes (And How to Avoid Them)

Most plugin issues don’t come from bad software – they come from small installation choices that add up over time. If plugins aren’t showing up, appear twice, or behave inconsistently, it’s usually one of the mistakes below.

1. Installing every format “just in case”: Many installers let you choose between VST2, VST3, AU, and AAX. Installing all of them might feel safe, but it usually creates clutter. You’ll often see the same plugin listed multiple times in your DAW, which makes it harder to know which version you’re actually using.
2. Ending up with duplicate plugins in the DAW: Duplicate plugins are almost always the result of installing multiple formats of the same plugin. This can slow down browsing, cause confusion when loading presets, and make older projects harder to manage if one version gets removed later.
3. Mixing VST2 and VST3 versions of the same plugin: Running both versions side by side can lead to inconsistent behavior. Presets may not transfer correctly, automation can behave differently, and projects may break if you uninstall one version down the line. Sticking to a single format avoids these headaches.
4. Assuming AU plugins work on Windows: AU plugins are macOS-only. Installing or scanning them on Windows won’t work and can waste time troubleshooting something that was never compatible in the first place.
5. Forgetting which plugin folder the DAW scans: Plugins won’t appear if your DAW isn’t scanning the folder where they were installed. This often happens when installers use default locations that don’t match your DAW’s plugin paths. Double-checking scan folders saves a lot of frustration.
6. Letting old or unused plugins pile up: Over time, unused demos, outdated versions, and redundant formats can clutter your system. This makes troubleshooting harder and slows down workflow when you’re searching for tools you actually use.

A clean setup keeps your DAW organized, saves disk space, and makes everything easier to manage in the long run.

Frequently Asked Questions