For fans of Chrome who prefer an ad-free browsing experience, recent announcements from Google are unlikely to go down well.
Google has quietly confirmed that it’s going ahead with a controversial change to its rules for Chrome browser extensions. Unless you’re a paid-up Enterprise user, this will mean that many content blockers (including the popular uBlock Origin and uMatrix ad blockers) will no longer work.
Here’s a closer look at what’s changed and why – along with possible workarounds.
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Chrome Ad Blocker Restrictions: What is set to change?
Ad blocking applications are extensions: i.e. small software programs designed to enable users to customise their browsing experience. To be included on the Chrome Extensions platform, apps must be built and deployed in accordance with Google’s specifications.
The current platform for Chrome extensions (Manifest V2) has been in place since 2012. Under it, content-blocking is handled by Chrome’s webRequest API. This allows users to filter out and block specified types of content (e.g. ads, pop-up videos and unsafe sites) before this content even reaches the browser.
Last year, Google started hinting at some of the changes that were in the pipeline as part of its upcoming revised rules for the extensions platform (Manifest V3). One change (announced in January) caused particular consternation among developers: for content blocking, Google now wants extensions to use a different API, declarativeNetRequest.
Under declarativeNetRequest, Chrome will basically decide whether to block content based on a ruleset limited to 30,000 individual rules. The trouble is that most ad blockers filter content by relying on vast, crowdsourced blacklisting rulesets, which tend to require way more than the declarativeNetRequest 30,000 rule limit. The argument is that fewer rules would mean a much less comprehensive blocking capability.
Fast forward to the end of May and there was some partial backtracking on the part of Google. Now it seems that if you’re a paying enterprise Chrome user, you will still be able to rely on the content-blocking capabilities of webRequest. All other users will have to rely on declarativeNetRequest as the primary content blocking API.
Reasons for the changes
Google states that its changes are always driven by the motivation of increasing the security, privacy and performance of Chrome extensions.
According to Google software engineer, Devlin Cronin, “It is not, nor has it ever been, our goal to prevent or break content blocking”.
The company has been especially keen to stress the likely impact of the change on browser performance. Currently, when a content filtering extension uses the webRequest API, Chrome basically refers the network connection request to the extension and waits for its decision on whether that connection should be allowed or blocked. With declarativeNetRequest, the extension lets the browser make the decision itself, which (theoretically at least) results in a faster connection.
These arguments have been greeted with some scepticism. As uBlock Origin author Raymond Hill pointed out, if users are experiencing performance lag, it’s much more likely to be down to pages bloated with trackers than the presence of content-blocking extensions.
One study, published on WhoTracks.me, analysed the performance of some of the most popular ad-blocking extensions, including uBlock Origin, Adblock Plus and Ghostery. This found that median decision time per-request is actually in the sub-millisecond region: i.e. far too insignificant to have any noticeable impact on the user experience.
The potential business benefits to Google from this move are hard to ignore.
When you’re choosing a browser to use, the ability to customise your experience with effective blocking and filtering extensions offers an attractive draw. But at the same time, Google still has its primary business to focus on: namely, generating ad revenue. In the space of a decade, Chrome has managed to get almost two thirds of the worldwide browser market share. With clear market dominance, it may take the view that it can afford to scale back the browser’s ad-blocking potential with a view to maximising ad revenues.
What happens now?
- At present, Manifest v3 is open to public view but is still subject to change. We can expect the proposed changes to be firmed up later this year.
- Developers are saying that certain ad blockers (e.g. UBlock Origin and uMatrix) will effectively no longer be able to work on the consumer version of Chrome unless they are completely remodelled.
- But you will still be able to get some ad blockers that work. These will be rule-based systems similar to AdBlock Plus. There are concerns that the limit of 30,000 rules will reduce the effectiveness of these extensions. However, according to 9to5Google, these limits may not be set in stone. According to Google: “We are planning to raise these values but we won’t have updated numbers until we can run performance tests…”.
- If you are thinking of switching to a different browser, Firefox may be your best bet and has always been my recommended browser for those concerned about security and privacy. Also (unlike the likes of Edge and Opera), it’s not based on Chromium. It’s the least likely to be affected by Google’s API changes.