System Data Unpacked
See what is really inside macOS System Data.
macOS files everything it cannot name under one line in Storage settings. This app opens it — simulator runtimes, Xcode caches, package stores, backups, snapshots — and lets you delete it item by item, in a window or from the menu bar.
The promise
It never deletes anything you did not click. Every item carries a badge — Safe regenerates on its own, Review goes to the Trash first — and every command is shown before it runs, including the ones that ask for your password.
What it does
Maps the disk
Categories largest first, each with a bar split into what is safe, what needs review and what is manual. Open one to see every item.
Remembers
A trend on every row, the change over the past week, and whether anything you deleted came back.
Speaks up
Optional alerts when a category grows unusually fast or space runs low, a weekly summary, and a one-tap way to free the safe items.
Window or menu bar
Open it from Applications like any app, resize it, leave it open. Or keep it in the menu bar with the size beside the icon. The icon can be switched off entirely.
Stays on your Mac
No account, no analytics. The only request it can make is an update check, off by default.
Nine languages
English, Turkish, Chinese, Japanese, German, French, Spanish, Korean and Russian.
Scriptable
--json prints the full inventory for your own tooling.
What it finds
- Simulator devices and runtimes
- Xcode DerivedData, archives, device support
- npm, pnpm, yarn, Cargo, uv, pip, Homebrew caches
- Model caches: Ollama, Hugging Face, LM Studio
- Docker and virtual machine disks
- iOS device backups
- Time Machine local snapshots
- Logs, diagnostics and temporary files
- Project build folders: node_modules, .build, Pods
- Anything else over 500 MB it cannot explain
What System Data actually is
What is System Data on a Mac?
It is the name Storage settings gives to everything it cannot file under Apps, Photos or Documents: caches, logs, simulator runtimes, local Time Machine snapshots, disk images, mail attachments, application support folders. It is not one thing, which is why the number gets large and why macOS shows you a bar instead of a list.
Why is my System Data so large?
On a Mac used for development it is usually a handful of folders: Xcode DerivedData and archives, simulator runtimes, npm and Homebrew caches, Docker disks, downloaded models. Each regenerates on demand, and together they pass 100 GB without anything being wrong.
Can I delete System Data?
Parts of it. Caches and build folders come back on their own, so removing them costs you a rebuild and nothing else. Snapshots and device backups are a decision rather than a cleanup. Nothing in macOS tells you which is which — this app labels every item before you touch it, and shows the command it will run.