How to actually lock an app on a Mac
Short answer first: macOS still has no built-in way to lock a single app behind a password or Touch ID. Apple's own position in its Support Communities is direct — "It is not possible to lock apps individually." That hasn't changed across macOS 26 or the macOS 27 "Golden Gate" feature list. Here's what people try instead, why each one falls short, and what actually works.
"Just create a second user account"
The most common answer to this question online — and the people asking usually reject it in the same breath they ask. It doesn't help when you're already logged in and just handing your Mac to someone for ten seconds; you'd have to log out first, which defeats the point. It also breaks shared file access and stops background tasks (renders, downloads, music) tied to your own session. As one person put it while asking for an alternative: "Without setting up different user accounts, is there a way to just password protect the Messages app?"
"Turn on FileVault"
FileVault encrypts your disk at rest — it protects your data if someone steals your Mac while it's powered off or locked at the login screen. It does nothing once you're logged in and your Mac is unlocked in someone else's hands, which is the actual scenario most people mean when they ask this question.
"Use Screen Time app limits"
Screen Time is built for managing a child's account, not protecting an adult's privacy on their own Mac. To use it as a lock, you'd set a 1-minute limit and then wait out that minute every time. It's also been documented to be bypassable through Spotlight — not a gap Apple built this feature to defend against in the first place.
"Encrypt a disk image / use chmod / hide it in Keychain"
None of these block an app from launching. A built-in app's data lives in ~/Library, not inside the app bundle you could encrypt or lock down with permissions — and Keychain tricks simply don't intercept the app opening at all. Multiple people have reported trying exactly this and finding the app opens anyway.
What actually works
The only approach that holds up is a dedicated app locker that controls the running process itself, not a workaround built for a different job. Most Mac app lockers still fall into the same trap as the methods above: they draw an overlay over the app, or check a password only when it first opens — so switching away and back, or simply waiting, leaves the app unlocked underneath.
Shoo! takes the more direct route: locking an app actually ends its process. There's nothing left running to bypass, no overlay to click through, and no gap when you switch back to an app you thought was locked — because it isn't open until you confirm with Touch ID. It works on any app, including Apple's own — Mail, Messages, System Settings — which is exactly where every method above stops working.
Try it free for 7 days — full functionality, no credit card, $17.99 once if you keep it.
Frequently asked
Can I lock just the Messages app on a Mac?
Yes — Shoo! lets you pick any individual app, including Messages, Mail, or System Settings, without touching anything else on your Mac.
Does macOS have a built-in app lock?
No. Apple's official position in its Support Communities is that "it is not possible to lock apps individually" on macOS. iOS gained this with iOS 18's Lock/Hide App feature in 2024; the Mac still hasn't, across two subsequent macOS releases.
Will macOS 27 add per-app locking?
Based on its published feature list, no — macOS 27 "Golden Gate" expands parental controls (app blocking, "Ask to Browse," time allowances) rather than adding a general per-app lock for adult users.