Google may break ad blockers with upcoming Chrome change

A Google plan to improve the Chrome web browser has triggered an explosion of concern that it'll also cripple extensions designed to block ads, improve privacy and protect against security problems.

Google's proposed approach would torpedo ad blocker uBlock Origin, tracker blocker Ghostery, privacy and password manager Privowny, JavaScript software blocker NoScript and a malware blocker from F-Secure, according to their developers.

In a statement Wednesday, though, Google said it's trying to improve Chrome while keeping all those extensions working.

"We want to make sure all fundamental use cases are still possible with these changes and are working with extension developers to make sure their extensions continue to work while optimizing the extensions platform and better protecting our users," the company said in a statement.

The controversy shows the difficulties that arise from Chrome's dominance 10 years after its debut. Google's browser accounts for 62 percent of website usage today, according to analytics firm StatCounter. But if a Google change causes problems, then extension authors and website developers can be stuck with it unless they can get millions of people to change to a different browser like Mozilla Firefox or Apple Safari.

Chrome's power also is amplified by the fact that other browsers, including Vivaldi, Opera, Brave and soon Microsoft Edge, use Chrome's open-source foundation, called Chromium.

Extensions let you customize web browser behavior to do things like take screenshots, manage tabs, disable websites' potentially risky JavaScript software and even replace photos of President Donald Trump with images of kittens. But ad blockers are a top extension use. Indeed, it was one of the uses Google specifically called for when it first revealed its Chrome extensions plan in 2008. uBlock Origin has been installed more than 10 million times, for example, according to Chrome Web Store statistics.

Ghostery developer Cliqz said Google's proposed change is radical, and threatened legal action if it goes forward.

"This would basically mean that Google is destroying ad blocking and privacy protection as we know it," the company said in a statement Wednesday. "Whether Google does this to protect their advertising business or simply to force its own rules on everyone else, it would be nothing less than another case of misuse of its market-dominating position. If this comes true, we will consider filing an antitrust complaint."

Chrome's Manifest v3 destiny

Google revealed the change way back in October as part of a broader plan to improve Chrome extensions. Some developers are only now noticing the part that could hurt ad blockers, called Manifest v3.

Manifest v3 is designed to improve Chrome extensions' performance, privacy and security. One part of that change, though, limits how extensions will be able to examine aspects of websites. The thorny limit affects how an extension can check if website elements originate from a list of hundreds of thousands of advertising sources. Google has proposed a limit of 30,000.

One extension designed to protect people who click on malicious links, Blockade.io, "will cease to function" under Google's Manifest v3 plan, said Brandon Dixon, who maintains the extension. "There is a 30K rule limit imposed, which is not enough to handle our ruleset (~250K)," Dixon said in a Wednesday mailing list post.

Safari and Firefox have embraced variations of Chrome's extensions technology, an approach that in principle makes life easier for extension authors trying to support multiple browsers. But Privowny's Daniel Glazman lamented the fizzling of an effort to turn Google's extensions technology into a web standard all browsers collectively develop and support.

The browser extension technology is "fully in the hands of Google, [which] can and will change it anytime based on its own interests only," Glazman said in a blog post Wednesday.

Google probably will amend its extensions plan, though not its aspiration to improve performance and security, Chrome team member Devlin Cronin said in a mailing list response Wednesday.

"This design is still in a draft state, and will likely change," Cronin said. "Our goal is not to break extensions."