Google's Plan to Limit Ad Blockers on Chrome Riles Developers

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Top developers behind ad-blocking and anti-tracking browser extensions say they’re alarmed by potential changes coming to Chrome recently disclosed in a public Google document. As a result, at least one company is now threatening possible legal action.

The proposed design changes would replace the API relied upon by privacy extensions like uBlock and Ghostery with another designed to “diminish the effectiveness of content blocking and ad blocking extensions,” the Register reported on Tuesday. The proposal would leave functional basic filters employed by Adblock Plus, which, the site noted, Google has reportedly paid to whitelist its own ads.

Extension developers say, among other potential consequences, the changes would kill competition among third-party ad blockers by placing new limits on their sophistication, ultimately making it harder to adequately shield Chrome users from undesired online tracking.


“This would basically mean that Google is destroying ad blocking and privacy protection as we know it,” Ghostery said in a statement. “They pretend to do this for the sake of privacy and browser performance, however in reality, users would be left with only very limited ways to prevent third parties from intercepting their surfing behavior or to get rid of unwanted content.”

Saying the change would exemplify a “misuse” of Google’s “market-dominating position,” Ghostery added that it would “consider filing an anti-trust complaint” if Google followed through.


Here’s how Ghostery described the proposal:

Today, browser extensions can use Chrome/Chromium’s webRequest API to block requests, which is the prerequisite to block ads and more importantly tracking scripts used to monitor users’ behavior and build personal profiles. In the proposed new model, the webRequest API will be replaced by the new declarativeNetRequest API. Essentially, this means an extension can send Chrome/chromium a list of blocking patterns and Chrome/chromium will do the blocking based on these patterns. It will, however, no longer be possible to modify or kill potentially dangerous or privacy-invading requests. The proposal would impose huge limitations on extension developers and would make it more difficult for users to protect themselves.


Initially telling reporters that its proposal is merely “subject to change,” Google signaled more strongly on Wednesday that it was preparing to rein in its plans. “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,” a Google spokesperson told Gizmodo.

The Register reported on related concerns raised by Raymond Hill, lead developer of uBlock Origin—a content-blocking extension with more than 10 million active Chrome users—who said his privacy software would “no longer be able to exist” if Google implemented the proposal described in the public document.


Hill added that the changes would likewise break uMatrix, a more advanced extension with granular controls for allowing users to block connections and content by data type.

Hill and other developers were seen discussing the matter on Chromium bug tracker, though a Google software engineer locked the thread on Tuesday after deleting several related comments. “I am another ad blocker developer (AdGuard), and from our perspective, the proposed change will be even more crippling to all ad blockers than what was done by Apple when they introduced their declarative content blocking API,” reads one of those undeleted comments.


The Google developers’ initial reasoning behind the changes, according to its documentation, is to provide “better privacy to users” by preventing extensions from reading “network requests made on the user’s behalf.”

This is a developing story.