Focus by Firefox is a new iOS app from Mozilla which takes advantage of iOS 9’s support for ‘content blockers‘. These are apps which can change the way Safari on iOS displays web pages, and most of those that have launched on the App Store focus on blocking web advertising.
Whilst Focus by Firefox does block some advertising, this isn’t its main objective. It’s more about protecting your privacy, by blocking web sites that leave tracking cookies. To do this, it uses a list from Disconnect, an add-on available for desktop browsers (reviewed by me in 2013). This is the same list that also powers desktop Firefox’s Tracking Protection in Private Browsing mode (and you can enable it on all pages using a hidden preference).
In addition, it can also block the download of web fonts, where web pages have specified a custom font that isn’t included on your iOS device as standard. This alleviates the issue where the text takes a long time to appear after a page loads, and is particularly welcome on my iPhone when out and about.
The settings that you choose will be made available in Safari, and any app that uses the Safari View Controller (this includes TweetBot, Reeder and others). It won’t include any third-party iOS web browsers like Google Chrome, or, ironically, Mozilla’s own Firefox browser for iOS, and any app that uses older methods of showing web content such as the Facebook app.
I found that Focus by Firefox made a marked improvement in page loading times on my devices – especially on my iPhone with web fonts disabled. Although this means that some web pages don’t quite look their best, they show up much more quickly, which is great when you’re on a train and approaching a tunnel. Users on metered data connections should find that they’re not using as much of their allowance each month.
On my iPad, where I still have web fonts enabled, I haven’t encountered any problems with web pages in the few weeks I’ve been using Focus by Firefox, so it gets my recommendation.
Focus by Firefox is free from the App Store, and is a universal app for all devices running iOS 9 or better.