HeaderMod by UtilsFactory

HeaderMod - Inject, update, edit, modify, override HTTP headers

A lightweight and open source browser extension that lets you intercept outgoing HTTP requests and inject, update, edit, modify, or override headers on a per-URL basis.

Key Features

• Define multiple header-modification rules
• Wildcard-based URL matching (e.g., .example.com/)
• Add or replace any request header (name + value)
• Enable or disable rules individually
• Persist rules in local storage for seamless browser restarts
• Dynamic toolbar icon indicates active rules

Usage

1. Click the HeaderMod toolbar icon to open the popup.
2. Click Add Rule to create a new entry, then fill in:
   • Header-Name and Header-Value
   • Optional URL Pattern (supports * wildcards)
   • Optional Notes for your reference
   • Enabled checkbox to toggle the rule
3. Modify or delete rules as needed.

What happens next

• Browse your sites as usual
• Each enabled rule is tested against the request URL
• Matching requests have their headers updated or appended before they leave the browser

Privacy

• HeaderMod does not collect, transmit, or share any personal data. All settings remain in your browser’s local storage and are never sent to any external server.

Whether you need to spoof headers for testing or inject custom metadata into requests, HeaderMod puts you in control.