Porn filter vs DNS vs app blocker on iPhone

The three kinds of porn blocker fail in different places. An app-based blocker stops working when you switch apps, a DNS filter can drop when you switch networks, and the iOS system content filter keeps running with the app closed until someone enters the Screen Time passcode.

What an app-based blocker stops

An app-based blocker ships its own browser and filters inside it, so it works only while you use that browser. A different browser gets around it, as does the in-app browser inside a social app, and deleting the blocker takes about four seconds.

iOS gives one app no control over another, so this is a platform limit, not the builders' fault.

What a DNS filter stops

A DNS filter changes where your phone looks up addresses. A blocked site's lookup returns nothing, so the page fails to load. It covers apps as well as browsers, which an app-based blocker does not.

Switching networks can hand you a different resolver, and the profile is a settings toggle away from off unless something locks it. It also sees only the name requested, not what is on the page, so it is coarse by design.

What the system content filter stops

iOS has a content filter built into Screen Time. An app can ask the system to turn it on, and from then on iOS does the filtering, not the app that asked.

There is no icon to delete, because the filter does not live in an app. It keeps working while that app is closed, and the switch that turns it off sits in Settings behind the Screen Time passcode. The short version has its own page: does a porn blocker still work when the app is closed.

Where the limit is

Anyone who knows the Screen Time passcode can turn the filter off. That is true of every iOS app that uses it, including ours, and an app that claims otherwise is wrong about how the platform works.

None of these is a wall. The system filter buys delay: the one-tap path is gone, and what replaces it is slow and dull enough to leave room to change your mind. That is a smaller promise than App Store screenshots make, and it holds up at 1am.

Which to pick

On iOS, use the system content filter if you want the version that does not depend on your cooperation. You can turn it on yourself through Screen Time in about five minutes, and the steps are in how to block porn on an iPhone. It costs nothing, which has its own answer in can you block porn on an iPhone for free.

If a blocker has come off your phone before, the mechanism was probably not the problem. That is covered in why porn blockers stop working.