When we released Witch 4, we released it only as a direct purchase; unlike Witch 3, Witch 4 is not available on the Mac App Store. You might be wondering why we made this decision, and the short answer is that we didn't—Apple did.

Here's the "too lazy, won't read" version: Witch 4 can't be in the Mac App Store because it can't be sandboxed.

And here's the longer version, in case you're interested in the details…

When the Mac App Store launched in January of 2011, there were only some basic requirements to be met to submit an app: The app couldn't be a System Preferences panel, it couldn't be a kernel extension, etc. We submitted all of our apps that met these simple rules (all but Butler and Leech, as I recall), including an application version of our Witch System Preferences panel.

Witch was accepted, and all was good. Then, in June of 2012, Apple began to require that all apps in the Mac App Store be sandboxed, which is a security mechanism that restricts what an app can do, especially as it relates to interacting with other apps.

Unfortunately, the way Witch (and many of our other apps) work is through something called the Accessibility API. And while you can, in general, sandbox an app that uses the Accessibility API, there's a huge restriction for apps like Witch (emphasis added):

With App Sandbox, you can and should enable your app for accessibility, as described in Accessibility Programming Guide for OS X. However, you cannot sandbox an assistive app such as a screen reader, and you cannot sandbox an app that controls another app.

Because Witch can work with other apps (closing windows, quitting the app, minimizing a window, etc.), it's not sandboxable. When Apple added the sandboxing rule, though, they included an exception for apps that were in the Mac App Store before sandboxing was required: Such apps could stay in the store, but they could not gain new features, only bug fixes.

So from mid-2012 through the release of Witch 4, that's what we did: Fixed bugs and didn't add features. We kept hoping Apple would change the rules for Accessibility and sandboxing, but no such changes happened. (Probably for good reason: sandboxing is all about keeping an app's actions within its own world, and accessibility allows interaction among apps.)

Unless/until Apple finds a way to make sandboxing and accessibility not mutually exclusive (it's doubtful they will do this), Witch cannot be in the App Store.