Short answer: Porn blockers fall into a few families: the controls built into your phone, DNS filters, blocker apps that use the phone's VPN slot, browser extensions, router filters, and accountability apps. Each one covers a different slice of your devices, and each one can be undone in a different way. A common approach is to combine a built-in or free DNS layer with something that adds delay before it can be switched off.
Version note: iPhone steps match Apple's iPhone User Guide for iOS 26. Android steps match Google's Android Help page and Cloudflare's and CleanBrowsing's pages for Android 9 and later. All pages were read on 21 Oct 2026. Apple's guide for iOS 27 lays out Screen Time differently, so if your menus do not match, check Apple's guide for your version.
Screen Time (iPhone and iPad). Apple's page for iOS 26 gives the route: open Settings, tap Screen Time, tap Content & Privacy Restrictions and turn it on, then tap App Store, Media, Web, & Games, tap Web Content, and select Limit Adult Websites. Add Website below Never Allow lets you add addresses to block. For the full walk-through see our iPhone guide: https://mamoriblocker.com/guides/block-porn-on-iphone/
How it is undone: Apple says a Screen Time passcode "must be entered before you can change the settings you've chosen for yourself or a child". If you set it yourself, you know it. Apple also describes Screen Time Passcode Recovery, which lets you reset the passcode with your Apple Account. So the lock is only as strong as who holds the code.
Family Link (a child's Android account). In the Family Link app a parent selects the child, taps Controls, then Google Chrome and Web, and chooses Allow all sites, Try to block explicit sites or Only allow approved sites. Google says "No filter is perfect", and that on iPhone, iPad and computers the child may have other browsers where the Chrome settings won't apply. This is designed for a parent managing a child, not for an adult on their own account. Our Android guide covers it in detail: https://mamoriblocker.com/guides/block-adult-content-kids-android-phone/
DNS is the lookup that turns a site name into an address. A filtering DNS service refuses to answer for domains in its adult category. Cloudflare says 1.1.1.1 for Families "automatically blocks DNS queries to domains associated with malware, phishing, or (optionally) adult content", with a separate option for blocking malware and adult content. CleanBrowsing's Family Filter "blocks access to all adult, pornographic and explicit sites", while its Adult Filter "does not block proxy or VPNs, nor mixed-content sites". CleanBrowsing's filters page lists three free filters (Family, Adult, Security), plus paid plans with more configuration.
Google's Android Help gives the path: open Settings, tap Network & internet, then Private DNS, pick Private DNS provider hostname, enter the provider's hostname and tap Save. Cloudflare's and CleanBrowsing's pages for Android 9 and later put Private DNS under Advanced, and Google says that if you can't find it, search Settings for "Private DNS". Cloudflare notes that once Private DNS is configured, your device uses that resolver on all networks, including cellular. Our DNS guide has the hostnames and cautions: https://mamoriblocker.com/guides/dns-to-block-porn/
What it misses and how it is undone:
Some blocker apps ask for the phone's VPN permission, not to send your traffic to a remote server, but to catch lookups on the phone itself. Whether a given app does that, or sends traffic elsewhere, is worth checking on its own privacy page.
Android's developer documentation sets the main limit: "There can be only one VPN connection running at the same time. The existing interface is deactivated when a new one is created." It also says a person can stop a VPN service from the VPN screen in Settings by disconnecting or forgetting the app, or by switching off always-on VPN. So another VPN, or a blocker that takes the slot, can switch your filter off without you meaning to.
Extensions customise one browser. Google's page describes adding Chrome extensions on a computer, says you can't add extensions when you browse in Incognito mode, and lists Allow in incognito as a per-extension setting, next to a switch that turns each extension on or off. Apple says Safari extensions on iPhone can be turned on or off at any time under Settings, Apps, Safari, Extensions. An extension does nothing for other browsers or apps, which is the main gap.
Cloudflare says configuring 1.1.1.1 on your router "applies the DNS setting to every device on your network", with no per-device changes. That includes a laptop, a console and a guest's phone. It does not follow a phone onto mobile data, and CleanBrowsing notes a device can still point itself at a different DNS server unless the router also forces DNS. Many consumer routers do not expose the firewall rules this takes. Router admin menus differ by maker, so follow your router's own documentation.
These apps are built around a second person seeing something, such as an alert or a report. They suit people who want that. They are a different idea from blocking, and they share a limit with any app on a device you control: unless something holds it in place, it can be removed or switched off.
On a device you control, every option above can be undone by you. The real question is how much time and effort stand between the urge and the off switch, and who holds the key:
For reference, Cloudflare's resolver page says it will "not sell or share Public Resolver users' personal data" and that 1.1.1.1 for Families uses the same privacy commitments. CleanBrowsing's privacy page says that for its free DNS services it does "not log or store any personally identifiable information". Read the current pages before relying on them.
Is there a free porn blocker?
Yes. Screen Time is built into iPhone, and Cloudflare 1.1.1.1 for Families and CleanBrowsing's free filters cost nothing to use. Their limits are the ones above.
Do DNS filters work on mobile data?
On Android 9 and later, Cloudflare says Private DNS applies on all networks, including cellular. On iPhone, manual DNS settings apply only to the Wi-Fi network you set them on.
Can I run two blockers at once?
Different layers can sit together. Two apps that both need Android's single VPN slot cannot.
Mamori is a newer app for iPhone, iPad and Android, built for adults who want to block adult content for themselves. It blocks 2.5M+ adult sites across the whole phone, not just one browser. On Android it is an on-device DNS filter using Android's VpnService, with no remote VPN server, no browsing logs and nothing uploaded. On iPhone and iPad it uses Apple's Screen Time web content filter plus its own blocklist. The list is built to also cover Japanese adult sites. Switching it off goes through a lock you choose in advance: a cooldown timer, a random phrase, or a PIN or passphrase that a trusted person can hold.
Honest limits: Android allows only one VPN at a time, so another VPN or blocker that takes the slot switches Mamori's filter off. No blocker replaces support from people or a professional, and Mamori has no accountability reports. For a child's device use Screen Time or Family Link as the base layer.
There is a 7-day free trial on the monthly and annual plans, plus a one-time lifetime option. No account, no tracking.
Last checked 21 Oct 2026. This guide is general information, not medical advice.