Google’s journey toward Chrome’s “Manifest V3” has been happening for four years now, and if the company’s new timeline holds up, we’ll all be forced to switch to it in year 5. “Manifest V3” is the rather unintuitive name for the next version of Chrome’s extension platform. The update is controversial because it makes ad blockers less effective under the guise of protecting privacy and security, and Google just so happens to be the world’s largest advertising company.
Google’s latest blog post details the new timeline for the transition to Manifest V3, which involves ending support for older extensions running on Manifest V2 and forcing everyone onto the new platform. Starting in January 2023 with Chrome version 112, Google “may run experiments to turn off support for Manifest V2 extensions in Canary, Dev, and Beta channels.” Starting in June 2023 and Chrome 115, Google “may run experiments to turn off support for Manifest V2 extensions in all channels, including stable channel.” Also starting in June, the Chrome Web Store will stop accepting Manifest V2 extensions, and they’ll be hidden from view. In January 2024, Manifest V2 extensions will be removed from the store entirely.
Google says Manifest V3 is “one of the most significant shifts in the extensions platform since it launched a decade ago.” The company claims that the more limited platform is meant to bring “enhancements in security, privacy, and performance.” Privacy groups like the Electronic Frontier Foundation (EFF) dispute this description and say that if Google really cared about the security of the extension store, it could just police the store more actively using actual humans instead of limiting the capabilities of all extensions.
The big killer for ad block extensions comes from changes to the way network request modifications work. Google says that “rather than intercepting a request and modifying it procedurally, the extension asks Chrome to evaluate and modify requests on its behalf.” Chrome’s built-in solution forces ad blockers and privacy extensions to use the primitive solution of a raw list of blocked URLs rather than the dynamic filtering rules implemented by something like uBlock Origin. That list of URLs is limited to 30,000 entries, whereas a normal ad block extension can come with upward of 300,000 rules.There’s considerable concern that Google is using its position as the world’s largest browser vendor to protect Google’s business model by hamstringing ad blockers and privacy-protection extensions. A few months ago, the EFF called Manifest V3 “deceitful and threatening.” The privacy advocacy group said Manifest V3 “will restrict the capabilities of web extensions—especially those that are designed to monitor, modify, and compute alongside the conversation your browser has with the websites you visit. Under the new specifications, extensions like these—like some privacy-protective tracker blockers—will have greatly reduced capabilities.”
The EFF poked holes in most of Google’s justifications for Manifest V3 changes, saying that malicious extensions are mostly interested in stealing data and that Manifest V3 only stops extensions from blocking data, not inspecting it, so Google isn’t doing much to stop bad actors. The report says performance also isn’t a valid excuse, citing a study showing that ad downloading and rendering degrades browser performance.
Whether it’s explicitly or implicitly, Google’s ad division seems to have an increasing influence on the design of Chrome. The company refuses to block tracking cookies until it can first build a tracking and advertising system directly into Chrome.
Several extension developers are working on solutions within the Manifest V3 sandbox. There’s no way of knowing the end-user impact until these solutions are developed and Google kills the existing extension platform, but loudly rolling out user-hostile changes seems like one of the few things that could hurt Chrome’s market share. Firefox is still out there, along with an endless number of Chromium forks.