Chrome Extension Manifest V3 Builder
Generate a Manifest V3 file for a browser extension. Fill in fields for name, version, permissions, action, service worker, content scripts. The output is a valid manifest.json you can drop into your extension directory.
Generated manifest.json
How to use the Chrome Extension Manifest V3 Builder
Fill in the name, version, and description, toggle the parts your extension needs (popup, service worker, content script), and list permissions and host patterns. The manifest.json updates as you go — copy it into your extension directory.
What manifest.json declares
Every browser extension is defined by its manifest.json — the file Chrome, Edge, and Firefox read to learn the extension’s name, which permissions it requests, which scripts run where, and how it appears in the toolbar. Manifest V3 changed the shape of several fields (background pages became service workers, host permissions split out from the permissions array), so older examples copied from the web often no longer load.
This builds a valid MV3 manifest from form fields for the parts people set most — name and version, an action popup, a service worker, content scripts, and the permissions and host-permissions lists — so you start from a file that loads rather than one you debug. If your extension needs a custom content_security_policy entry, build the policy with the CSP policy builder and drop it into the manifest.
Common use cases
- New extension — start from a manifest that loads under Manifest V3.
- MV2 to MV3 — see the modern shape for service workers and host permissions.
- Permission scoping — request only the permissions your extension actually needs.
- Content scripts — declare which pages your scripts inject into.
- Learning MV3 — read a correct manifest to understand each field.