Developer launches Filtr to block ads across iOS and macOS apps

Developer Kaylee Serena Calderolla has released Filtr, a new privacy tool designed to block advertisements within iPhone, iPad, and Mac applications. Bundled as an additional feature for her existing Wipr browser ad blocker, Filtr utilises the new URL filters capability introduced in iOS 26 and macOS 26 to block ad domains at the network level. The service operates via a pre-filter blocklist stored on the user’s device, with server-side verification routed through Apple’s servers to maintain user anonymity. Filtr is available for an annual subscription of $5 or a one-time lifetime payment of $25.

Filtr is the first application reported to utilise the URL filters feature, a capability that allows developers to block access to specific websites or domains at the network level rather than solely within a browser. Calderolla, who previously launched Wipr to prevent ads and tracking code from loading in Safari, described the implementation process as a "nightmare" due to sparse documentation from Apple. Despite these technical hurdles, the tool provides immediate relief from ads across apps, with some ad slots displaying greyed placeholder spaces where content would have loaded.

The service relies on a pre-filter blocklist that is stored locally and kept up-to-date via automatic updates in the Wipr app. When a website is accessed, the pre-filter list determines if it is not on the block list, allowing the site to load normally. If the list identifies a potential match, it confirms the request against Calderolla’s servers. These verification requests are routed through Apple’s servers as a proxy, ensuring that app developers cannot identify who is querying their blocklists. Calderolla’s privacy policy states that her apps do not collect personal data and do not require access to personal information to function.

There are limitations to the tool’s scope. Filtr does not block ads served from the same network as the website being visited, meaning users will still encounter advertisements within apps such as Facebook, Google, or Reddit. Blocking these domains would likely break the applications entirely. For users seeking comprehensive ad blocking, Lifehacker noted that using mobile websites instead of apps allows Wipr to continue blocking ads in browsers other than Safari.

Ad blockers are generally recommended for security and privacy, with the FBI citing them as a defence against online harms. Traditional ad blockers often fail to prevent tracking from ads within applications, leaving users exposed when not on home Wi-Fi networks protected by tools like Pi-hole. Filtr addresses this gap by extending protection to the device level, offering a solution for users who spend significant time on mobile and desktop applications outside of their home networks.

Wipr remains a universal app available for $5 in the Apple App Store, working across all Apple devices. Filtr is offered as an in-app purchase add-on, costing $5 annually or $25 for a lifetime payment. The release marks a significant step in device-level privacy tools, providing users with greater control over their digital environment beyond the browser.