Lock Down Content Filtering Loopholes with Gertrude for iOS
Apple Family and Screen Time controls can be used to restrict access to adult content on iPhone and iPad, but recent iOS updates have unintentionally introduced hard-to-fix loopholes. These loopholes can be used to get around traditional content filtering and gain access to explicit content. Some of these loopholes can be patched manually, but those solutions are often overly complex or simply ineffective.
Enter Gertrude Blocker (iOS 17+), the first app to systematically close several of these gaps. After reading their announcement, I tried it hands-on and quickly saw why it’s a game‑changer.
The Gertrude App Closes Common Loopholes in Screen Time
Apple’s Screen Time does block adult content in browsers, but it struggles to filter content in non-browser apps. Gertrude fills several of these crucial gaps and provides a simple onboarding experience so that you don't need to be technically savvy.
Disabling GIF Searches in Messages
The iMessage “#images” GIF extension can be used to discover explicit images, leading many parents to want to remove GIF searching entirely since results can't be reliably filtered.
If your iPhone is connected to a DNS
Content Policy
that blocks websites with a network firewall, blocking the address smoot.apple.com could be used to disable GIFs in iMessage.
However, if you're relying on Screen Time alone to block websites on an iPhone or iPad, it won't be possible to block this domain by adding it to the website blocklist.
Fortunately, the Gertrude Blocker app installs a local content filter that effectively blocks GIF searching from iMessage and other messaging apps.
If you're using Screen Time to filter content on your iPhone or iPad, we highly recommend installing Gertrude Blocker and using it to block GIFs in iMessage.
Blocking Images in Spotlight Search
In iOS 18, Spotlight Search can display web-based image previews—even if you've disabled Safari and all browser apps on the iPhone or iPad.
Gertrude Blocker prevents Spotlight from loading any image results or previews.
Spotlight Internet Results can also be completely disabled using Supervised Mode , but blocking the images from displaying is good enough for most people.
Disabling Images in Apple Maps
Even with strict content controls, Apple Maps can display explicit image results. Similar to iMessage, some parents discover that content filtering can't be applied reliably to Apple Maps and would rather disable those images entirely.
Gertrude Blocker can be configured to suppress image thumbnails while allowing Apple Maps functionality.
Self‑Protection and Tamper‑Resistance
If enabled correctly (we'll discuss later on), the Gertrude Blocker app can prevent itself from being removed so that these restrictions aren't bypassed.
When properly configured, trying to delete the app will display this message:
Blocking Apple.com and AI Features
Gertrude Blocker can block apple.com (not typically feasible with Safari filters or Screen Time).
Additionally, on supported devices, Gertrude turns off Apple’s AI features entirely, guarding against exclusions in Apple’s native controls.
Prerequisites to Enable Gertrude Correctly
Because of restrictions imposed by Apple, the Gertrude app requires one of the two following things to be true:
- The iPhone / iPad is set up with a child's Apple account (age < 17) and is part of an Apple family group.
- An adult's iPhone / iPad is set up with Supervised Mode
The app will not work unless one of these is true, and you won't be able to make use of its features until then.
For more information about what's required and a walkthrough of how to set up your devices, I've written an article explaining how to elevate permissions for iPhone so apps, like Gertrude, can be correctly enabled.
Frequently Asked Questions
What is Gertrude?
Gertrude provides a solid Mac application that captures screenshots and blocks websites. They prioritize an approach similar to our "default-deny" approach for Mac computers that restricts the entire internet, except for specifically allowed websites.
The iOS app was developed to help plug several gaps that parents noticed with Apple Screen Time. I'd strongly suggest checking out their official blog post for more details about why and how they overcame limitations imposed by Apple.
Can the Gertrude iOS App be used if I'm self-managing my own device?
I was able to give the iOS app a fairly rigorous test using a self-managed approach. I think it makes a great tool for both parents and adults trying to block adult content on their own iPhones.
It's a bit more relevant for parents, though, since it seems to work best with Apple Family. I was able to get most of the features to work on a Supervised iPhone as well, in case you're self-managing and can't use Apple Family.
Are there other ways to block GIFs in iMessage?
If your iPhone is connected to DNS Content Policy , then GIFs in iMessage can be blocked by blocking this domain:
smoot.apple.com
You can't block this domain using Apple Screen Time since there are limitations related to blocking apple domains.