How do app blockers work on iPhone?

App blockers on iPhone work by asking iOS to do the blocking. They use Apple’s Screen Time API: you grant the blocker Screen Time access, you pick apps in a picker that Apple controls, and iOS covers those apps with a block screen at the times the blocker sets. App blocking on iPhone runs through iOS this way, and Apple has to approve each blocker’s developer before the app can use it.

That design explains most of what people ask about blockers: why they need Screen Time permission, what Apple’s Family Controls approval is, why a block keeps working after you close the app, and why a blocker can’t see which apps you picked. This page walks through each part using Apple’s developer documentation and its WWDC sessions. We make Calma, an app blocker built on the same API, and we point out where apps differ.

What is the Screen Time API?

The Screen Time API is a set of frameworks Apple added in iOS 15 (WWDC21) that give approved apps access to the same restrictions Screen Time uses. Apple’s session Meet the Screen Time API describes three frameworks, plus a fourth for the block screen’s look:

The API was built for parental control apps first. In iOS 16, Apple added what it calls individual authorization, which lets you authorize an app on your own iPhone. Apple said this means the API “can be used to build more than just parental controls apps.” That change opened the API to apps you use on your own phone, like Opal, Brick and Calma.

Why do iPhone app blockers need Screen Time permission?

App blockers need Screen Time permission because that is how iOS lets a third-party app shield other apps. Its technical name is Family Controls authorization, and Apple’s WWDC22 session calls Family Controls “essentially a gateway” to the rest of the Screen Time API.

Three things happen around that permission:

1. Apple approves the developer first. Before an app that uses Family Controls can ship, the developer has to request a special entitlement. Apple reviews the app and adds the entitlement if it approves.
2. You approve the app on your iPhone. On your own device, iOS shows an alert. If you continue, it asks for Face ID or Touch ID, according to Apple’s AuthorizationCenter documentation. Apple’s WWDC22 demo also shows the device passcode as an option.
3. You can take it back. At WWDC22, Apple said each authorized app gets a switch in Settings, under Screen Time and in the app’s own settings page, that removes its access. If you revoke it, Apple’s docs say every token the app received is voided.

The “Family” in the name comes from the API’s parental control origin. With individual authorization, Apple notes that the child-account rules, like not being able to sign out of iCloud or delete the app, “do not apply.”

What do “Family Controls entitlement” and “authorization status” mean?

They are Apple’s names for the two approvals above. The entitlement is Apple’s approval of the developer, and the authorization status is the answer you gave on your iPhone. This part is for curious readers and developers who ran into the terms in Apple’s documentation. You don’t need it to use a blocker.

The Family Controls entitlement. Apple’s entitlement page describes it as a value that shows “whether the app can request or revoke authorization to provide parental controls.” Without it, an app can’t even ask you for Screen Time access. Before the app ships on the App Store, the developer’s Account Holder has to request the entitlement from Apple, with the same request for each Screen Time extension, like the ones that run schedules or draw the block screen. Apple reviews the app and, if it approves, adds the entitlement to the developer’s account. So every App Store blocker that shields apps through Screen Time went through that review.

Who approves the request on the iPhone. Apple’s Family Controls overview describes two cases. For a child, a parent or guardian in the same Family Sharing group approves it. For an individual, the owner of the device approves it, with Face ID or Touch ID. Blockers you use on your own phone ask as an individual.

The authorization statuses. Apple’s AuthorizationStatus page lists four values a blocker can read:

The last one is real and fairly new: Apple’s page for approvedWithDataAccess lists it as available from iOS 26.4. The EU details are in the next section.

Why does a block keep working when the blocker app is closed?

A block keeps working when the app is closed because iOS enforces it, not the app. When a blocker adds apps to a shield through Managed Settings, the setting lives in iOS. The blocker doesn’t need to be open, or even running in the background, for the shield to appear.

Timing works the same way. With Device Activity, the blocker registers a schedule (say, 10 PM to 7 AM) or a usage threshold (say, 30 minutes of Instagram) with iOS. When the time arrives, iOS calls a small extension inside the blocker, and that extension turns the shield on or off. In the WWDC21 demo, Apple’s engineer set a daily shield “even when Homework hasn’t run since being setup.” Apple summed it up as running code “even when your app is not being used.”

One detail from Apple’s DeviceActivityCenter documentation: iOS calls those start and end events when the device is in use. A schedule that starts at 10 PM kicks in the first time the phone is used after 10 PM.

You can see how firmly iOS holds these settings in Opal’s own help center. It warns that if you delete Opal during a strict session, “your apps continue to be blocked”, and explains how to reset the Screen Time connection. The shield stayed in iOS after the app that set it was gone.

What is the screen you see when an app is blocked?

The screen you see is a shield, drawn by iOS over the blocked app. Apple’s docs say shielding dims the app’s icon on the Home Screen and adds an hourglass, and when the app launches, iOS covers it with a view the blocker can configure.

Blockers can change the shield’s background, icon, title, subtitle and up to two buttons, using Managed Settings UI. A separate extension decides what each button does. Apple’s WWDC21 session lists two outcomes for a button press: close the blocked app, or wait and redraw the shield.

That is why block screens look so different from app to app while working the same way underneath. Calma’s, for example, says the app is resting, with a single Back to calm button on scheduled blocks and daily limits.

Can app blockers see my data?

For the most part, no. App blockers on iPhone see coded tokens instead of your app names, and they can’t read what you do inside other apps. At WWDC21, Apple said that with this API “your customers’ usage data will be invisible outside of their device.”

Here is how that works in practice:

• The picker is Apple’s, not the blocker’s. When you choose Instagram and TikTok, you choose them in Apple’s FamilyActivityPicker, which Apple describes as a way to pick apps “without revealing their choices to the app.” The blocker gets back opaque tokens, not names.
• Tokens work, but don’t reveal. The blocker passes those tokens to iOS to shield or monitor the apps. Apple says an ApplicationToken lets an app restrict apps “without access to personal user data.”
• Even button taps come back as tokens. When you tap a shield button, iOS tells the blocker’s extension which token was involved. Apple’s docs say iOS doesn’t provide the name of the app “to preserve the Family Sharing group’s privacy.”
• Names stay in a sealed box. The extension that draws the shield does get the app’s display name, so a block screen can say “Instagram is resting.” Apple runs that extension in a sandbox that blocks network requests and keeps the data inside the extension. Usage charts inside blocker apps work the same way: Apple’s DeviceActivityReport extension draws them in a sandbox with no network access.
• What gets measured is time, not content. Device Activity counts the time an app is frontmost on screen. None of these frameworks gives a blocker the posts, messages or videos inside another app.

The one exception: the EU data access option

Since iOS 26.4, Apple offers a second level of permission called approved with data access. It lets an app see real app identifiers, the domain names of websites you visit and category names instead of tokens. Apple limits it to devices in the EU signed in with an EU Apple Account, and only one app per device can hold it. On devices outside the EU, Apple says that status is never returned.

A few more details from Apple’s docs, in plain words. The app also needs a second entitlement, Family Controls App and Website Usage, and you have to authorize that access explicitly. If you later give data access to a different app, the first app’s status goes back to notDetermined. Developers can build and test this in any region with an Apple-provided provisioning profile, but customer installs only get it in the EU, according to Apple’s FamilyActivityData page.

The Screen Time API is only one part of an app’s privacy picture. A blocker can still collect other things, like analytics about how you use the blocker itself. The App Store privacy label is the place to check. Calma needs no account, keeps its rules on your iPhone, and can’t see what you do inside apps. Its label lists Usage Data, not linked to you.

What can’t an app blocker do on iPhone?

An iPhone app blocker can only restrict what Apple’s frameworks expose. (It is also different from Apple’s Face ID app lock, which keeps other people out but doesn’t stop you.) Four limits come up most:

• It blocks whole apps, not features inside them. Apple’s ShieldSettings cover apps, app categories and websites. A blocker can shield Instagram, but it can’t hide only Reels or keep only direct messages open. For that, use the app’s own settings, like the ones in our guide to blocking Instagram on iPhone.
• It shields up to 50 apps at a time per setting. Apple’s docs say an app can shield “up to 50 application tokens at once”. Whole categories, like all social apps, can also be shielded as a group.
• It can’t block some system apps. Brick’s FAQ, for example, says you can block any iPhone app “except Phone, per Apple policy.”
• It has the final word only if it’s the strictest. Apple’s docs say iOS decides the effective state from all the settings it receives, and at WWDC22 Apple said “the most restrictive setting always wins.” Two blockers on the same app can get tangled. Brick’s help page, for example, asks you to turn off Screen Time access for other blockers when a block isn’t working.

Websites are a separate case. The API can shield web domains, and some blockers use that. Calma blocks apps only, not websites.

Hard lockout, pause or scheduled rest: what’s the difference?

Blockers built on the same Apple tools feel very different because each one chooses when the shield turns on and what its buttons do. Most fit one of three styles. We make Calma, so weigh our summary of the others with that in mind, and check each app’s help pages.

Sources for the table: Brick FAQ, Opal help on Sessions, and one sec’s iOS 27 setup guide, which says one sec “relies on so called ‘Shortcuts Automations’” to trigger its pause. one sec also offers Screen Time based blocking, which its help center covers in a page on Screen Time API issues.

Calma’s exits are specific. A focus session can end early with a 3-second hold. Any routine can be switched off in the app. Open limits show an Open app button. Scheduled blocks and daily limits show only Back to calm. For how the styles compare in daily use, see hard blocker or gentle pause and whether a pause before opening apps works.

How is this different from Screen Time’s own limits?

Third-party blockers shield apps “much like Screen Time does,” as Apple put it at WWDC21, but Screen Time’s own default lets you past the limit. Apple’s iOS 26 guide put it plainly: “By default, Screen Time limits can be ignored once reached.” With Block at Downtime off, the same guide said, “you see a reminder that it’s downtime, but you can choose to continue using the apps.” Our guide to what Block at Downtime does covers that switch in detail.

In iOS 27, the names changed. App Limits became Time Allowances and Downtime became Screen Time Schedule, with Always Allowed for apps and contacts that stay available, as Apple’s iOS 27 guide describes. That guide doesn’t repeat the line about ignoring limits, so check what your own limit screen offers. Our list of iOS 27 Screen Time changes maps every old name to the new one.

Two other places moved in iOS 27. The Screen Time passcode, which must be entered before anyone can change your Screen Time settings, now sits under Settings > Screen Time > Passcode & Management > Lock Screen Time Settings. Apple’s iOS 27 user guide and its support article on the passcode agree on that path. In the iOS 26 guide, Lock Screen Time Settings sat directly on the Screen Time screen. And turning Screen Time off is now Settings > Screen Time > Manage Screen Time > Turn Off App & Website Activity, per Apple’s iOS 27 setup page. See our guides to the Screen Time passcode and turning off Screen Time for both versions.

The difference with a third-party blocker is who writes the buttons. Screen Time’s limit screen offers Apple’s options, like Ignore Limit (see how to stop bypassing Screen Time limits). A blocker’s shield shows only the buttons its developer chose, and each one does what the blocker’s extension decides. Our Calma vs Screen Time comparison covers those options side by side.

What to look for when choosing an app blocker

Since most App Store blockers run on the same Apple frameworks, the real differences are in the rules and the way out. Before you pick one, check:

• When blocks turn on. A schedule, a daily time limit, a number of opens, or a manual session.
• What the block screen lets you do. Nothing, wait, or continue, and whether that changes by rule.
• What it collects outside Screen Time. The App Store privacy label, and whether it needs an account.
• Price and devices. Some blockers cover only iPhone. Calma is iPhone only, and it needs a subscription after a 3-day free trial: $3.99 a week, $9.99 a month or $39.99 a year in the US as of October 5, 2026.

To weigh those points against your own habits, try a five-question quiz that scores eight blockers. If a gentle, scheduled version sounds right, see how Calma sets it up on the app blocker page. For the broader case of cutting back without deleting apps, start with how to block distracting apps without deleting them.

Sources

All checked on September 28, 2026. Apple sources rechecked, and sources 11 to 13 added, on November 9, 2026.

1. Apple Developer, Meet the Screen Time API, WWDC21 session and transcript.
2. Apple Developer, What’s new in Screen Time API, WWDC22 session and transcript.
3. Apple Developer Documentation: Family Controls, AuthorizationCenter, FamilyActivityPicker, FamilyActivitySelection, approvedWithDataAccess, Requesting the Family Controls entitlement.
4. Apple Developer Documentation: Managed Settings, ManagedSettingsStore, ShieldSettings, ApplicationToken, ShieldActionDelegate.
5. Apple Developer Documentation: Managed Settings UI, ShieldConfigurationDataSource.
6. Apple Developer Documentation: Device Activity, DeviceActivityCenter, DeviceActivityMonitor, DeviceActivityEvent, DeviceActivityReport.
7. Apple Support, Set Screen Time Schedules and Time Allowances on iPhone (iOS 27) and the iOS 26 version.
8. Opal Help: How do I hard reset my Screen Time settings and How to use Sessions.
9. Brick: FAQ and Apps aren’t blocking? How to fix it.
10. one sec Help: Initial Shortcuts Setup on iOS 27+ and Screen Time API Issues.
11. Apple Developer Documentation: Family Controls entitlement, AuthorizationStatus, Family Controls App and Website Usage entitlement, FamilyActivityData.
12. Apple Support, Create, change, or remove a Screen Time passcode on iPhone (iOS 27), the iOS 26 version, and Set up Screen Time for yourself on iPhone (iOS 27).
13. Apple Support, How to create a Screen Time passcode on an iPhone or iPad, published October 28, 2026.