Docker Desktop was using 67GB on my Mac. I didn't notice until my build failed with "no space left on device" and I started digging. 67GB. For containers I hadn't run in months, images I'd pulled once for a quick test, build cache from projects I'd abandoned, and a VM disk file that had ballooned to 40GB and refused to shrink. If you're a developer running Docker on macOS, you're almost certainly in the same situation. Docker is designed to cache aggressively and clean up never. On Linux, Docker stores everything directly on the filesystem, so standard disk tools can see it. On macOS, Docker runs inside a Linux VM — and everything it stores is hidden inside a single disk image file. That file only grows. It never shrinks on its own. This guide covers every category of Docker disk usage on macOS: what it is, how to find it, how to clean it, and how to stop it from coming back. How Docker Uses Disk on macOS Before we start cleaning, it helps to understand why Docker on macOS is a special kind of disk hog.…