Image: GitHub
Why it mattersOn a developer Mac, "System Data" is often the biggest line in Storage settings. There is no built-in way to open it. A tool that names each item and reads the delete command out first is useful today.
Open System Settings on a developer Mac, then General and Storage. "System Data" is often the biggest line. Apple gives you no way to see what is inside. System Data Unpacked, a free menu bar app at Jarvis322/macos-sysdata on GitHub, opens it and lists every item.
The repository was first committed on 5 September 2026. It had 1,447 stars when read, 56 days later. It was ranked 25th on Trendshift's daily list the same day. The code is on GitHub under a proprietary licence. The binary is signed and notarised by Apple from version 0.3.2 on. A universal build runs on Intel and Apple Silicon from 0.3.7.
What it finds
The README says a scan returns around 180 items in 19 groups. The groups cover local Time Machine snapshots. They cover simulator devices and runtimes. They cover Xcode DerivedData and Archives. They cover the whole Homebrew prefix. They cover the npm, pnpm, yarn, pip, uv, CocoaPods and Gradle stores. They cover Cargo and Go module caches. They cover Ollama and Hugging Face models, one row per model. They cover Claude Code, Codex, Grok, Copilot, Gemini and Kilo local data. They cover Docker build cache and project volumes. They cover Parallels, UTM, VMware and VirtualBox disks. They cover iOS device backups and log stores. They cover project build folders such as node_modules and .next under Desktop, Documents, Developer and Projects.
Each row carries a real size measured on disk. Each row also carries one of three badges. Safe is for items that regenerate on their own, such as caches. Review is for items that cost something to delete, such as a simulator runtime or a re-download. Manual is for items the app cannot remove on your behalf. The info button then shows the command or the settings path.
The delete command is shown first
Before anything runs, the confirmation shows every operation word for word. The example in the README is As administrator: rm -rf /Library/Logs/DiagnosticReports/*. It is not a count of items. A Copy button puts the whole plan on the pasteboard. Review items go to the Trash, so a wrong click can be undone for 30 days. Safe items are deleted outright, because they come back on their own.
Every root action runs as a one-off osascript prompt. The README says this is why the app asks for the password each time. It is why the app installs no privileged helper, no launch daemon and no kernel extension. The scan history is a local file. The README says the only network request the app makes is a once-a-day update check on GitHub. That check is off by default.
What it still cannot do
Deleting the macOS dyld cache is blocked by the system, even as root. The README says so in the Simulator devices row. Purgeable space is reported in the header. A tooltip says it is macOS's own estimate and not space you can plan around. The README's own test writes 6.44 GB on a test machine. The write cost 6.44 GB of real free space. It took nothing from the 3.55 GB purgeable pool.
The app runs on macOS 14 and later. It is written in Swift 6. It is translated into nine languages, the last five of them machine-assisted.
Source
This item was written by an AI system from the linked source. Reveneau is responsible for what it publishes.
Get AI News in your inbox
New developer tools, model and agent releases, and how teams are actually using them to release software. Short, and only when there is something worth reading.