Install @t Filter

Pick the device to protect and follow the steps. You need an installation code: it links the device to your household.

Locked Screen Time (adults and children, no paid account)

A Screen Time passcode held by someone else (a witness or parent) stops the settings below from being undone without them. That person chooses and types the passcode on the device: AT Filter never sees it and never receives it. Setting names follow Apple's help pages; wording may differ slightly between versions.

Install the AT Filter profile first (the "Profile" button in the steps above), then follow this guide.

iPhone (iOS 18, 26)

Settings → Screen Time. If it is off, turn it on (depending on version: "Turn On Screen Time" / Turn On App & Website Activity).
Have the witness or parent create the passcode and type it themselves: Screen Time → Manage Screen Time → Change Screen Time Passcode. Choose a passcode the user does not know and cannot guess.
Screen Time → Content & Privacy Restrictions: turn it on.
Content & Privacy Restrictions → App Store, Media, Web & Games → Web Content → Limit Adult Websites.
Content & Privacy Restrictions → iTunes & App Store Purchases: do not allow Installing Apps or Deleting Apps.
Content & Privacy Restrictions → Allow Changes to Settings: set Accounts to Don't Allow and, if listed, Passcode. Go through the whole list and refuse anything that affects AT Filter; if your version has a setting for profiles or VPN, refuse it too.

What this lock does not guarantee

The Apple pages consulted do not say Screen Time prevents removing a configuration profile or a VPN. Treat the AT Filter profile as removable: only a supervised device makes it non-removable (see the stronger protection).
The lock only works while the passcode stays secret. Anyone who knows it can undo everything, and AT Filter can neither read nor check it.
On Mac, the pages consulted describe install, delete, passcode and account blocks for iOS and iPadOS devices: do not assume a Mac is locked the same way.
Other iOS or macOS versions may rename these settings. If in doubt, the console shows the device's real state.

Apple sources

iPhone or iPad

On the iPhone or iPad, open this page in Safari (not Chrome), tap “Download the iPhone profile”, then “Allow”.
DNS filter
AdGuard and CleanBrowsing also enforce SafeSearch and restricted YouTube in all apps; Cloudflare only closes adult sites.
This iPhone is supervised (prepared with Apple Configurator)Profile removal passcode (4 to 16 characters, keep it to yourself)
Only applied on a supervised iPhone: on an ordinary iPhone, Apple always lets the profile be removed.
Apps and sites to close (supervised iPhone)
These lists only apply on a supervised iPhone. On an ordinary iPhone, Apple ignores them: only fill them in if the iPhone was prepared with Apple Configurator.
Apps to block (one bundle ID per line)
Bundle IDs of the apps (see the App Store, or ask the AT Filter team). Examples: net.whatsapp.WhatsApp, org.whispersystems.signal, com.revolut.revolut.
Always-allowed sites (one per line)Always-blocked sites (one per line)
Allowed and blocked sites are added on top of the adult filter: they never replace it.
Commitment message (read before accepting the profile)
Shown at installation, like a code of conduct the user agrees to.
Open Settings → “Profile Downloaded” (at the top) → Install, enter the iPhone passcode, then Install again.
Check: Settings → General → VPN & Device Management → “AT Filter”.

The profile closes adult and malicious sites across the whole device (Cloudflare 1.1.1.3 encrypted safe DNS), enforces SafeSearch in Safari ("Limit Adult Websites" filter), and sets age ratings (apps 12+, movies PG-13, TV-14, no erotic books).

It does not: analyse images or pages, block a specific app or site, or enforce SafeSearch in other browsers (Chrome, Firefox… — Apple does not allow it on an ordinary iPhone). The user can remove the profile. On a supervised iPhone, it also closes the chosen apps and sites, and the profile cannot be removed without the passcode.

Going further, for free

Screen Time: Settings → Screen Time → Content & Privacy Restrictions (on) → Content Restrictions → Web Content → “Limit Adult Websites”. Then “Lock Screen Time Settings” with a passcode you keep, different from the iPhone one.

Supervision with Apple Configurator (Mac, free; the iPhone is erased once)

Back up the iPhone (iCloud), then install Apple Configurator from the Mac App Store.
Connect the iPhone by USB, select it, then Prepare → Manual Configuration → tick “Supervise devices” → create an organisation (free, no paid account). The iPhone is erased.
After setup, download the profile here with “This iPhone is supervised” ticked and a removal passcode, and install it (or add it in Apple Configurator: Add → Profiles).
The profile can no longer be removed without the passcode, DNS can no longer be turned off, Safari filters adult sites and its private browsing is closed (iOS 26), and installing other profiles or VPNs, erasing the iPhone and deleting apps are blocked.

In your browser

The AT Filter extension blocks adult sites and enforces SafeSearch in the browser, even without the app. Pick yours.

Download the AT Filter extension (atfilter-extension-chrome.zip) and unzip it.
Open chrome://extensions, turn on "Developer mode", then "Load unpacked" and choose the folder.
Enter the installation code in the extension. The extension store version is coming soon; on Windows the AT Filter installer already enforces it in Chrome.
YOUR-CODE

Finally: check

When the device is linked, it shows in your console as "Filter on". Tick as you go:

The AT Filter app is installed and the install code entered.
The filter is on (VPN request accepted).
Device administrator and Accessibility are enabled.
The device appears in the management console, status "Filter on".

Open the console to check

Get my installation code

Enter the email address of your @t Filter account: we send you a code valid for 2 hours.

No account yet? Create my household