About Blue Guard
Blue Guard stops your device loading the ad and tracker networks that most pages and apps pull in. Blocked content is never downloaded, so pages tend to load faster and use less data.
It is made of four parts:
- The app, where you choose what to block and which sites to leave alone.
- A Safari content blocker, which hands Safari its rules.
- A network extension, which runs app-wide blocking when you turn it on.
- A widget extension, which carries the home screen widget showing the daily blocked count, and a Control Centre toggle for app-wide blocking.
The two mechanisms
Safari blocking works by giving Safari a rule list. Safari matches those rules against requests and page elements itself. Blue Guard is not asked anything as you browse, receives no page content, and gets no record of what you opened. iOS requires you to enable a content blocker yourself, in the Settings app, which is why setup starts outside the app. See Setting it up.
App-wide blocking works on domain names. When your device looks up a domain that is on the block list, Blue Guard answers the lookup on the device and the request never leaves. Everything else is forwarded to a public resolver so it can be answered. It covers every app rather than Safari alone. It is off until you switch it on.
How blocking works describes both in more detail.
What it is not
It is not a VPN. It carries none of your traffic and it hides no addresses. Turning on app-wide blocking does ask iOS to add a VPN configuration, because a packet tunnel is the only mechanism iOS gives an app for filtering domain lookups. Your traffic still goes where it always went.
It is not a browser. Safari does the browsing; Blue Guard only supplies the rules.
It does not read pages. No part of the app receives page content.
What it cannot do
- Safari blocking covers Safari. iOS does not let one app reach inside another to remove page elements, so element hiding in another browser or in an app's own web view is out of reach.
- App-wide blocking matches whole domains. An advert an app serves from its own domain cannot be separated from the rest of that domain, so it stays.
- Any blocker doing real work will sometimes stop a script a site depends on. When that happens, allowing the site is the fix.
- Filter rules go stale as trackers move. Corrections ship with app updates.
What it costs
Blue Guard is free in full, with no trial, no paid tier, and no feature held back. The app includes a tip jar for anyone who wants to fund the work, handled entirely by Apple's App Store, and a tip unlocks nothing.