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Free tool

Manifest V2 → V3 migration checker

Paste your Manifest V2 manifest.json and see exactly what to change for Manifest V3 — service worker, action, CSP, host permissions, and more. All in your browser.

How it works

Every MV2 pattern, mapped to MV3.

  1. 01

    Paste

    Drop in your Manifest V2 manifest.json.

  2. 02

    Review

    See each deprecated key and its exact MV3 replacement.

  3. 03

    Update

    Apply the changes and update your background code to match.

FAQ

Migrating to MV3, explained.

Chrome has phased out Manifest V2 — the Web Store no longer accepts new MV2 extensions and is disabling existing ones. MV3 is now required to publish and stay published.

It scans your manifest for MV2 patterns — background pages/scripts, browser_action/page_action, string CSP, string web_accessible_resources, and host patterns in the wrong key — and tells you the exact MV3 replacement for each.

No — everything runs in your browser. Your manifest never leaves your device.

It covers the manifest.json changes. You'll also need matching code changes — for example moving from chrome.browserAction to chrome.action, and from blocking webRequest to declarativeNetRequest — in your background service worker.

Migrated and re-shipped? Watch your churn.

Big updates can shake loose users. UserFeed's uninstall feedback and drop-off funnel tell you whether the migration cost you anyone — free for one extension.

Explore UserFeed