Last week I ran MegaCleaner on my development MacBook for the first time in months. It found 127GB of junk. Not "maybe junk" — actual build artifacts, stale caches, and orphaned data from tools I use every day.

My 512GB drive had 47GB free. After cleaning, I had 168GB free. That's a quarter of my entire disk reclaimed.

Here's the full breakdown of what was hiding on my machine.

The Scan Results

MegaCleaner scans 29 categories (21 developer tools + 8 general system categories). On my machine, almost everything had something to report. Here's what it found, from largest to smallest.

Xcode DerivedData + Simulators — 42GB

This is always the big one. I do iOS work across several projects, and Xcode is relentless about caching.

DerivedData: 16GB across about 30 project folders, most of which I haven't opened in months. Xcode never cleans these up. Ever.

Old simulator runtimes: 19GB. I had iOS 17.2, 17.5, and 18.0 runtimes still installed. I'm building against iOS 18.4 now.…