Your Mac is storing 30 GB of Apple asset packs, and you can see them
AssetsV2 holds downloadable system assets and it is enormous on a developer Mac. What is in it, what counts against your disk, and what can be removed.
If the System or System Data figure on your Mac is far larger than seems reasonable and nothing in your home folder accounts for it, there is a specific folder worth looking at. It is not documented anywhere a normal person would find it, and on the Mac these measurements come from it holds 30 GB.
Look at yours
du -sk /System/Library/AssetsV2/* 2>/dev/null \
| sort -n | tail -12 | awk '{printf "%5d MB\t%s\n", $1/1024, $2}'Every folder there is named com_apple_MobileAsset_ followed by what it holds. That naming is the whole trick to reading this folder: the suffix tells you which feature downloaded it.
What the large ones are
| Asset | What it is | Removable |
|---|---|---|
iOSSimulatorRuntime | Downloaded simulator runtimes for Xcode | Yes, with simctl |
UAF_Siri_Understanding | On device Siri language models | Only by removing the language |
LinguisticData | Text analysis data per language | No, managed by macOS |
UAF_Photos_MagicCleanup | On device model for Photos editing | No |
UAF_Speech_AutomaticSpeechRecognition | Offline dictation models | Turn off offline dictation |
DictionaryServices | Dictionaries per language | Remove languages you do not use |
The one worth acting on
On a Mac with Xcode installed, simulator runtimes are usually the largest thing in the folder and the only entry with a supported delete command. They are stored here as system assets in addition to the devices in your own Library, which is why simulator storage can be surprisingly large in two places at once.
xcrun simctl runtime list
xcrun simctl runtime delete <build or identifier>
xcrun simctl delete unavailableOn the same Mac, /Library/Developer/CoreSimulator held another 10 GB alongside the 25.5 GB here, which is the pairing worth knowing about: the simulator devices and their data are a separate folder from the runtime images this page is about.
The ones you should leave
Everything else in this folder is a machine learning model or language resource that a macOS feature depends on. macOS redownloads what it needs, so deleting by hand achieves a temporary reduction and a later download, and on the sealed parts of the system it will not work at all. Removing a language you genuinely do not use, in System Settings, is the supported way to shrink the language assets.
Why this never shows in the storage screen
macOS sorts these into System or System Data with no breakdown, which is exactly the limitation of that screen. The only way to see the split is to measure the folder, which is what the command above does.
Common questions
What is /System/Library/AssetsV2 on a Mac?
It is where macOS stores downloadable system assets: simulator runtimes, Siri language models, speech recognition data, dictionaries and on device machine learning models. On a Mac measured in September 2026 it held 30.6 GB.
Does AssetsV2 count against my disk space?
Yes. Although the path begins with /System, df reports the folder on the data volume, so its contents are part of what fills your drive. It is counted under System or System Data in the storage screen with no breakdown.
Can I delete Apple asset packs to free space?
Only the ones with a supported command. Simulator runtimes can be removed with xcrun simctl runtime delete, and language assets shrink when you remove a language in System Settings. Deleting the rest by hand fails on the sealed volume or is redownloaded.
Why are simulator runtimes stored in two places?
Downloaded runtime images are kept as system assets under AssetsV2, while the simulated devices and their data live under /Library/Developer/CoreSimulator and your own Library. On one measured Mac that was 25.5 GB and 10 GB respectively.