Less than a day after the launch of iOS 9, Apple’s latest operating system, content blocking software is at the top of the app charts worldwide.

In the UK, two content blockers have hit the top 20 paid apps, with Purify at number 11 and Peace at number 12. In the US, the take-up has been even starker: Purify is at number 5 in the charts, and Peace is the top paid app in the whole country.

The popularity of the apps suggests that mobile adblocking - which has been enabled in Apple’s default Safari browser for users who have upgraded to iOS 9 - could become even more widespread than it is on desktop. A 2014 report suggested that on desktop almost 150 million browsers were using some form of adblocker.

The rise of adblocking has proved concerning for web publishers, many of whom rely largely or exclusively on display advertising for revenue. In Germany, four major broadcasters have now tried and failed to win in court against Eyeo, which makes one of the largest adblockers: AdBlock Plus. Publishers argue that blocking display ads hurts their business, and is unethical because it allows users to view content without paying the implied price of an ad impression.

The developer of Peace is Marco Arment, a high profile iOS developer known for being the first employee of Tumblr, as well as his previous apps Instapaper and Overcast. Peace isn’t his first entry into adblocking: a side-effect of Instapaper, the first of a class of apps which download content to read off-line, was stripping the adverts from saved content, in order to make them cleaner and easier to read.

But Peace is Arment’s first app where ad blocking is the primary focus, and he has addressed the ethical concerns of such a move a number of times. “We shouldn’t feel guilty about this,” he said in the app’s launch announcement. “The ‘implied contract’ theory that we’ve agreed to view ads in exchange for free content is void because we can’t review the terms first — as soon as we follow a link, our browsers load, execute, transfer, and track everything embedded by the publisher. Our data, battery life, time, and privacy are taken by a blank check with no recourse.”

Arment has expressed his hope that blocking bad ads will lead to publishers being forced to adopt “better monetisation methods”, from selling adverts directly (and so cutting out the data-collecting middlemen) to collecting direct payments from readers. To that effect, Peace offers the ability to “whitelist” sites easily from the share menu in Safari, if a user wants to support a specific publisher.

But others argue that the rise of adblocking will instead have a counterproductive effect, driving publishers to platforms where adverts – and tracking code – cannot be blocked. Facebook and Apple News are two such platforms, as Casey Johnston, a technology journalist, writes: “Driving publishers to Facebook will not get rid of invasive trackers; it’s only declaring allegiance to the most comprehensive one, which has bought data from brokers with hundreds of millions of consumer profiles, and whose privacy policy doesn’t prevent it from selling users’ data, as long as it is anonymised (a process widely considered insufficient for privacy protection).”

If adblockers do continue to prove popular with users, they could also be a major weapon in Apple’s arsenal against its key competitor, Google. Unlike Apple, which makes the majority of its revenue from hardware sales, Google’s income still relies largely on web display advertising. As such, it is unlikely to ever encourage the use of adblocking to the same extent as Apple, and has previously banned adblockers from the Android app store. Currently, however, Android users can block ads, but only if they install a specially downloaded browser.