But the same feature can be used maliciously to hijack users’ login credentials or insert additional ads into web pages, which was the rationale for Google to change how it works in Manifest V3. In particular, they block domains that will load ads and stop sending information from the browser to any file of thousands of tracker domains that collect data about Internet users. Ad blocking extensions use this feature to block incoming and outgoing traffic between certain domains and the user’s browser. Web Request is powerful and flexible, and it can be used for both good and bad purposes. The example Google gives developers shows an extension script that prevents the browser from sending traffic to “”: Under the currently active specification – Manifest V2 – browser extensions can use an API feature file called a web request to monitor traffic between the browser and a website and modify or block requests to certain domains.

The changes in Manifest V3 are part of a planned overhaul of the Chrome browser extension’s manifest file specification, which defines the permissions, capabilities, and system resources that an extension can use. For Google, though, adhering to MV3 will have a significant impact on the overall ad blocking role on the modern web. Although Firefox has a much smaller share of the desktop market than Chrome, it could be an opportunity for the Mozilla product to really define itself. Google’s strategy has been heavily criticized by privacy advocates – the Electronic Frontier Foundation has done so as an outspoken opponent – but the search company has not been affected. For Google, adherence to MV3 will have a significant impact on the overall role of ad blocking

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