Compared to Manifest V2 content blockers, Manifest V3 extensions can be less powerful due to the artificial rules limits of Manifest V3. For users, it can mean that the installed content blocker does nothing at all.ĪdGuard's new browser extension for Chrome demonstrates that content blockers are possible under Manifest V3. In fact, the developers note that even the basic filter lists, which is the primary list of AdGuard, may be disabled in the worst case, as it has more than 30,000 rules. The developers have added warnings to the extension that inform users when the rules limitation is forcing the extension to reduce the number of rules that it supports. When the limit is exceeded, only the first 5000 rules will be applied by the content blocker, while all other rules have no effect.ĪdGuard MV3 Browser takes that into account. These compete with each other then when it comes to the limits.ĭynamic rules have an even stricter limit of 5000, which includes a limit of 1000 regular expression rules. Now imagine that other extensions are installed that rely on rules. It is easy to reach the 330,000 rules limit with just one extension. Users may add their own custom rules to many content blockers or subscribe to more rules listings. The default configuration of uBlock Origin uses 80435 network filters and 45243 cosmetic filters that is already more than four times the minimum guaranteed rules limit. The number may sound like much, but when you realize that modern content blockers rely on tens of thousands of even hundred thousands of rules, the limitation becomes apparent right away. Any one extension has guaranteed access to 30,000 rules. One of the main issues of Manifest V3 is that it imposes a fixed limit of 330,000 rules for all extensions installed in Chrome.

While they managed to produce a working content blocker based on Manifest V3, they concede that it has certain limitations that Manifest V2 content blockers did not have. The developers note that the new APIs of Manifest V3 caused a lot of headache during development. Work on the extension started in mid-2021.

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