Modifly
Install

Install Modifly in Chrome.

Get automatic updates by installing Modifly from the Chrome Web Store. For local development, you can still download and load the extension yourself.

Add to Chrome Download for local installation

Local package: version 0.1.0 · ZIP archive · Chrome 145+

The Modifly extension with an active rule and the form for adding a new rule.
Chrome Web Store Recommended install with automatic updates.
Chrome 145+ Older versions cannot load this build.
Local option Load the unpacked extension for development.
01

Recommended

Install from the Chrome Web Store

  1. 1

    Open Modifly in the Chrome Web Store

    Visit the Modifly extension page in Chrome.

  2. 2

    Add the extension

    Select Add to Chrome, then confirm by selecting Add extension. Chrome installs Modifly and keeps it updated automatically.

02

Local development

Download and load it locally

Use this option when you need an unpacked copy for development or testing. Store installs are recommended for everyday use.

  1. 1

    Download and unzip the archive

    Download modifly-v0.1.0.zip, then extract it into its own folder. Keep that folder on disk while using the extension.

    Chrome needs the folder containing manifest.json, not the ZIP file itself.

  2. 2

    Open the extensions page

    Enter chrome://extensions in the address bar, or choose Extensions → Manage extensions from the Chrome menu.

  3. 3

    Turn on developer mode

    Enable the Developer mode switch in the top right corner of the extensions page. The Load unpacked button appears once it is on.

  4. 4

    Load unpacked

    Select Load unpacked, choose the folder you extracted in step 2, and confirm. Modifly appears in the list and its icon is added to the toolbar.

03

First run

Run the extension

Pin the icon

Select the puzzle-piece icon in the Chrome toolbar, then the pin beside Modifly, so the popup stays one click away.

Add a rule

Open the popup on the site you are working on, enter a hostname, header name, and value, then select Add rule.

Allow site access

Chrome asks whether Modifly may access the hostname you configured. Choose Allow to activate the rule.

Reload and check

Reload the target site so it issues fresh requests, then confirm the header in the Network panel of DevTools.

Full getting-started guide

04

Troubleshooting

Install problems

There is no “Load unpacked” button.

Developer mode is still off. Turn on the switch in the top right corner of chrome://extensions and the button appears immediately.

Chrome reports “Manifest file is missing or unreadable.”

The selected folder is not the extension root. Choose the folder that contains manifest.json directly, and make sure you extracted the ZIP rather than selecting the archive itself.

Chrome says the extension requires a newer version.

This build sets a minimum of Chrome 145. Check your version under chrome://settings/help, let Chrome update, then restart the browser and load the extension again.

The extension disappeared after I restarted Chrome.

Unpacked extensions are loaded from their folder on disk. If that folder was moved, renamed, or deleted, Chrome drops the extension. Restore the folder or load it again from its new location.

How do I update to a newer version?

Download the new ZIP, extract it over the existing folder, then select the reload icon beside Modifly on chrome://extensions. Your saved rules stay in your Chrome profile.

How do I remove it?

Select Remove beside Modifly on chrome://extensions. That deletes its stored rules along with the extension; the extracted folder stays on disk until you delete it yourself.