Full Disk Access on a Mac: what it grants and why apps ask
· 6 min read
Full Disk Access grants an app permission to read the data macOS keeps behind a privacy gate: the Mail store, Messages, Safari’s browsing data, Time Machine backups, and the folders that otherwise produce a “would like to access” prompt one at a time. It is a data permission, not administrator rights, and it does not let an app modify the system or watch your screen.
You grant it in System Settings, Privacy & Security, Full Disk Access. An app cannot grant it to itself, and the switch requires your password or Touch ID.
What it actually covers
macOS protects certain locations regardless of file permissions. An app without Full Disk Access cannot read them even when it is running as you, and even when you can open the same files in Finder.
The protected set includes:
~/Library/Mail, where Mail stores messages and attachments- Messages history
- Safari’s browsing data and cookies
- Time Machine backups
- Desktop, Documents, Downloads, iCloud Drive, removable volumes and network volumes, which otherwise each produce their own permission prompt
- The privacy database that records these grants
That last one is the reason the permission is worth thinking about rather than clicking through. An app with Full Disk Access can see which other apps have which permissions.
The practical effect is that the app stops asking: one grant covers the protected set, which is why backup software, disk tools, sync clients and file search apps ask for it during setup.
What it does not grant
The name oversells it. Full Disk Access does not mean full control of the disk.
It is not administrator or root. The app still runs as you, with your file ownership and permissions. It cannot read another user’s private files on a shared Mac simply because it holds this permission.
It cannot modify the system. System Integrity Protection and the signed system volume are separate mechanisms, unaffected by anything in the Privacy pane.
It does not include the other permissions. Screen Recording, Accessibility (which is control of the Mac, the real one to be careful with), camera, microphone, location and App Management are each granted separately, in their own list on the same settings page.
It does not defeat FileVault. A locked volume stays locked. This permission applies while you are signed in.
It grants no network access. An app that can read your Mail store and also talks to a server is a combination worth thinking about, but the second half is not something this switch decides.
How to grant it, and how to take it back
- Open System Settings, then Privacy & Security.
- Scroll to Full Disk Access and click it.
- Unlock with Touch ID or your password if prompted.
- Switch on the app you want, or click the plus button, authenticate, and choose the app from Applications.
- If macOS offers Quit & Reopen, take it. The app usually cannot use the new permission until it restarts.
Removing it is the same list. Switch the app off, or select it and click the minus button to remove the entry entirely. Nothing is deleted and no data is lost; the app simply stops being able to read protected locations, and will say so or start prompting again.
Worth doing once a year: read that list top to bottom. It accumulates, and an entry for an app you deleted months ago is a good prompt to switch off the ones you no longer use.
To clear every Full Disk Access grant at once and start again from an empty list:
tccutil reset SystemPolicyAllFiles
Every app that needs it asks again the next time it runs, so expect prompts. Use it when the list has become unreadable, not as routine maintenance.
Which requests are reasonable
The question is not whether an app asks, it is whether the ask matches the job.
Reasonable. Backup tools, because a backup that skips Mail and Messages is not a backup. Disk usage and cleanup tools, because the space in question is often exactly in those protected folders. File search apps, for the same reason. Migration and sync tools. Security software.
Worth a pause. Anything that could do its job without seeing your Mail store: a screenshot tool, a media player, a menu bar utility for the weather. If the connection between the feature and the permission is not obvious to you, the app should be explaining it in the setup screen.
Look at the pairing. The combination that deserves thought is broad file access plus a network connection plus no clear statement of what leaves the machine. Each part alone is normal. Together, you are relying on the developer’s word, so it should be a word they have put in writing.
A practical example of an honest ask: Everywhere requests Full Disk Access because it catalogs every filename on the Mac, and without it Mail attachments and parts of the home folder are simply invisible to it. If you decline, it works on what it can reach and names the folders it is missing rather than failing quietly. It also has no network code at all, and verifies its license offline by signature, so the permission and the machine’s traffic are separate questions.
Terminal is the one to think hardest about
Granting Full Disk Access to Terminal (or any other shell app) does not grant it to Terminal alone. It grants it to everything you run inside Terminal, including scripts you paste from a web page.
That is genuinely useful: mdfind results from protected locations, rsync copies that include Mail, du on a folder that otherwise reports zeros. It is also the broadest grant on the list, because the set of programs it covers is open-ended.
Two habits make it reasonable. Grant it when you need it and switch it off afterwards. And read anything you paste into a shell that holds it, particularly a command someone else wrote for you.
mdfind: searching a Mac from the Terminal covers what changes in search results when Terminal has the permission and when it does not.
When missing access looks like a broken app
The symptom is rarely an error message. It is emptiness: a backup that finishes suspiciously fast, a disk tool reporting far less used space than About This Mac, a search returning nothing for files you can see in Finder.
Before assuming a bug, open Full Disk Access and check whether the app is listed and switched on. If you granted it and the app still cannot see anything, quit the app completely (Cmd-Q, not just closing the window) and open it again. Permission changes are read at launch.
Spotlight cannot find a file you know exists covers the other reasons search comes up empty, most of which are not permissions at all.
Questions
Is Full Disk Access dangerous to grant? It is meaningful, not dangerous by itself. You are trusting the app with your Mail, Messages and backups. Grant it to software you would trust with those things anyway, and use the list to withdraw it when you stop using the app.
Why does an app ask again after an update? macOS ties the grant to the app’s code signature. A rebuilt or re-signed app, or one replaced by a different copy, can read as a new app and needs the permission again.
Can I grant access to one folder instead of the whole protected set? Sometimes. The Files and Folders section of the same settings page lists per-folder grants that apps requested individually, and you can switch those off one by one. Whether an app works with only those depends on the app.
Does an app on the Mac App Store need this? App Store apps are sandboxed, which limits what they can reach even with the permission. That is why tools that must see the whole disk are often distributed directly by their developers instead.