ModHeader Legacy is a browser extension that allow you to modify HTTP request and response headers. It is a fork of the legacy 2.5.4 version of the original ModHeader extension which transitioned to 3.0.0 in April 2020.

Credit: All credit for this extension goes to the original author, Hao Nguyen. Everything below this line is from the original version and all other parts of this extension remain exactly the same except for the name.

If you find ModHeader useful, please consider making a donation. If you use it for your company project, please ask your company to make a monthly donation!

• Add/modify/remove request headers and response headers
• Enable header modification based on URL/resource type
• Add comments to header
• Multiple different profiles
• Sorting headers by name, value, or comments
• Append value to existing request or response header
• Export and import header
• Clone profile
• Cloud backup
• Tab locking!

Feel free to send pull requests to add new features to ModHeader. It will benefit everyone! That said, I reserve the rights to reject pull requests that does not seem useful, or if they add too much complexity for very little benefits.

You may fork and redistribute ModHeader for a small group of friends / colleagues, but please do not impersonate ModHeader, or try to sell it for a profit. If you use ModHeader in any commercial product, please let me know.

ModHeader does not require any extra tool for building. Simply load the src directory into Chrome / Firefox to start local development.

If you need to use ModHeader for Selenium tests, please visit: modheader_selenium