# System Data on a Mac | ByteSweep Docs

> See what is inside macOS System Data with ByteSweep and where to clean each part.

Canonical: https://bytesweep.app/docs/clean/system-data.html
Last updated: 2026-11-02

## System Data on a Mac

macOS lumps a lot under System Data. This page, on Mac only, shows you what's in it.

### On this page

- See what's in it

### See what's in it

1. Open **What's in System Data**from**Free up space**.
2. Read **Where it goes**.
3. Follow the button for each part: **Open Clean**,**Open Developer Files**,**Open Chats and Mail**or**Open Storage**.
4. Press **Measure Again** afterwards.

A folder macOS keeps closed shows no size, not 0 bytes. [Full Disk Access](https://bytesweep.app/docs/setup/permissions.html) opens most of them. Time Machine snapshots have **Thin Snapshots**.

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Updated 2026-11-02. Something wrong here? Write to [support@bytesweep.app](mailto:support@bytesweep.app).