Google is closing the last loopholes that let ad blockers survive in Chrome. The company's transition to Manifest V3—its new extension framework—is entering its final phase, and it's killing every workaround that developers created to keep uBlock Origin and similar blockers functional. Microsoft Edge and Opera have confirmed they'll follow Chrome's lead.

Here's the technical background. Manifest V3 replaced the webRequest API that ad blockers used to intercept and block network requests before they loaded. Google claimed the old API was a security and performance problem. The replacement, declarativeNetRequest, is more limited by design—specifically, it caps the number of blocking rules extensions can use.

For simple ad blockers, that limit might work. For sophisticated tools like uBlock Origin, which maintains hundreds of thousands of filter rules across multiple lists, it's crippling. So developers got creative, finding ways to work within V3's constraints while maintaining functionality.

Google is now systematically closing those workarounds. Extensions that used clever tricks to exceed rule limits are being flagged as non-compliant. The grace period for V2 extensions is ending. And Chrome's extension store is starting to delist blockers that don't meet V3 requirements.

Raymond Hill, uBlock Origin's developer, was blunt about the situation: V3 makes a proper ad blocker impossible. He created uBlock Origin Lite as a V3-compatible version, but it's significantly less capable. It's the difference between a scalpel and a butter knife.

The stated justification is security and performance. Chrome argues the old API let extensions do too much, creating privacy and stability risks. Totally reasonable if you ignore that Google makes 80% of its revenue from ads. When a company's business model involves showing ads claims to be improving browser security by limiting ad blockers, skepticism is warranted.

From an engineering perspective, Google absolutely could design a secure API that enables effective ad blocking. They chose not to. That's a policy decision dressed up as a technical requirement.

Microsoft and Opera's decision to follow Chrome is predictable—they all use Chromium as their foundation. Maintaining a separate extension API would be significant work, and neither company has business reasons to fight for ad blocking. Microsoft has its own ad business; Opera has commercial relationships with advertisers.