Filtr, a new privacy tool from the developer behind the popular Safari ad blocker Wipr, extends ad blocking beyond the browser to virtually every app on iPhones, iPads, and Macs. The tool, built by Kaylee Serena Calderolla, relies on a feature in Apple’s iOS 26 and macOS 26 called URL filters, which blocks ads and their tracking code at the network level rather than within a single browser.
Wipr, Calderolla’s existing ad blocker for Safari, prevents ads from loading in the browser, stopping both the visual clutter and the tracking code advertisers use to follow users across websites. Filtr, offered as a paid add-on to Wipr, takes that same approach system-wide. For $5 per year (or a $25 lifetime purchase), users can install a URL filter on their device that consults a regularly updated blocklist to prevent ad-serving domains from loading in any app.
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How Filtr works under the hood
Apple’s URL filters feature allows developers to block access to specific domains at the operating system level. Calderolla told TechCrunch that Filtr is the first app to use the feature, partly because Apple’s documentation was sparse, making implementation a challenge she detailed in a May blog post.
Filtr stores a pre-filter blocklist on the user’s device, which is kept up to date through automatic updates in the Wipr app. When an app attempts to contact a domain, the pre-filter quickly checks whether the domain is on the blocklist. If it might be, the request is verified against Calderolla’s servers via Apple’s proxy, so the app developer never learns who is querying the list.
Calderolla’s privacy policy states that her apps do not collect personal data, and the URL filter feature itself does not require access to personal information to function.
What Filtr blocks — and what it doesn’t
In testing, Filtr immediately reduced the flood of ads in most apps, with some ad slots appearing as grayed-out placeholders. The relief was immediate, according to TechCrunch’s Zack Whittaker, who tested the tool and has been a paying Wipr user for years.
There are caveats. Filtr cannot block ads served from the same domain as the app itself — for example, ads within the Facebook, Google, and Reddit apps — because blocking the entire domain would break the app entirely. For those services, using their mobile websites within Safari, where Wipr’s browser-level blocking works, remains an alternative.
No ad blocker is perfect, but reducing exposure to ad networks is a meaningful privacy gain. The FBI has recommended ad blockers as a defense against online harms, and tools like Filtr extend that protection beyond the browser for the first time on Apple devices.
Filtr is available as an in-app purchase within Wipr, which costs $5 in the Apple App Store and works across all Apple devices.
