Manifest V3: Ad Blockers and Extensions Face Major Changes

Introduction

The transition to Manifest V3 (MV3) — the new browser extension standard led by Google — has sent shockwaves through the developer community. While it promises improved security, performance, and privacy, it also disrupts how many powerful extensions, particularly ad-blockers and network filters, operate.

For developers and users alike, MV3 marks the start of a new phase: adapt or disappear.

🧠 What Is Manifest V3?

Manifest V3 is the latest specification for browser extensions in Chrome and Chromium-based browsers. It introduces stricter permission models, a new service worker architecture, and a move away from the once-powerful webRequest API.

In theory, this makes extensions faster, safer, and more privacy-friendly. But in practice, it limits what developers can do at the network level — where tools like uBlock Origin, Ghostery, and NoScript once thrived.

⚡ The Big Change: From webRequest to declarativeNetRequest

Under Manifest V2, extensions could intercept and modify network requests in real-time using the webRequest API. This gave ad-blockers full control to analyze, block, or rewrite requests — essential for advanced filtering and privacy protection.

Manifest V3 replaces this with declarativeNetRequest, a new system where extensions must declare rules in advance, leaving browsers in charge of enforcement.

This change means:

• Less flexibility: Ad-blockers can’t apply dynamic rules easily.
• No real-time script injection or modification.
• More dependency on the browser’s internal filtering capabilities.

🧩 Ad-Blockers Under Pressure

Leading ad-blockers have spent years adapting to the new framework, but not without compromise.

uBlock Origin, for example, launched a new version — uBlock Origin Lite — built specifically for MV3. It runs more efficiently but with reduced power and fewer customization options.

AdGuard and Ghostery have also released MV3-compatible versions, but each admits the same limitation: they can’t block as deeply or as dynamically as before.

For privacy-focused users, this means fewer protections against trackers and a more standardized, less flexible browsing experience.

🔒 Security vs. Control

Google’s reasoning is clear: giving extensions full control over network traffic introduces privacy and security risks. Malicious extensions could log or manipulate user data.

By moving to a declarative model, Chrome ensures:

• Fewer attack surfaces for malicious actors.
• Predictable performance.
• Greater consistency across browsers.

However, many privacy advocates argue this sacrifices user control for corporate convenience — especially since the web advertising ecosystem benefits from less aggressive blocking.

🌐 Cross-Browser Fallout

While Chrome leads the shift, the ripple effects reach far beyond.

• Microsoft Edge (built on Chromium) follows suit, enforcing similar limits.
• Opera and Brave are adopting MV3 with modifications — Brave, for instance, keeps its own built-in ad-blocker independent of MV3.
• Firefox continues to support MV3 but retains the powerful webRequest API for now, offering a haven for power users and developers seeking full functionality.

This means browser choice is now more important than ever for users who value control and privacy.

🔮 The Future of Network-Level Extensions

As Manifest V3 becomes the new standard, the extension ecosystem faces a split:

• Compliance and adaptation: Tools that evolve with MV3 constraints.
• Innovation elsewhere: Developers building standalone apps or proxy-based solutions.
• Resistance: Users and developers migrating to privacy-first browsers like Firefox or Brave.

In the long run, AI-driven filtering and cloud-based ad-blocking could fill the gap — integrating intelligence into browsers at a deeper level without relying on old APIs.

💬 Conclusion

The Manifest V3 transition is more than a technical update — it’s a philosophical turning point for the open web.

It challenges how much freedom and transparency developers and users should have within browsers.
Ad-blockers may adapt, but the era of full user-side network control is coming to an end.

For the web’s next chapter, innovation will depend on finding a balance between security, privacy, and independence — one rule at a time.