# Header Editor Pro – Modify HTTP Headers

> Free and open source HTTP header editor. Add, modify or remove request and response headers with unlimited profiles, per-domain filters and one-click pause. No account, no telemetry, no data collection. Available in 7 languages.

Canonical page: [https://chrome-stats.com/d/header-editor-pro-free](https://chrome-stats.com/d/header-editor-pro-free)

## Overview

- **ID:** `header-editor-pro-free`
- **Platform:** Firefox
- **Type:** Firefox add-on
- **Status:** Available
- **Publisher:** Charly Brown
- **Category:** web-development,privacy-security
- **Daily users:** 6
- **Weekly downloads:** 2
- **Version:** 2.6.2
- **Last updated:** 2026-09-04
- **First published:** 2025-08-13
- **Size:** 69 KB
- **Data as of:** 2026-09-06
- **Store listing:** [Firefox Add-ons Store](https://addons.mozilla.org/firefox/addon/header-editor-pro-free/)
- **Website:** [https://testacode.github.io/header-editor-pro-free/](https://testacode.github.io/header-editor-pro-free/)

## Description

Header Editor Pro is a free, open source HTTP header editor for developers. Add, modify or remove request and response headers, with no account, no telemetry and no limits.

<strong>What it does</strong>
<ul><li>Request and response headers — set or append, each one individually toggleable</li><li>Unlimited profiles — no three-profile ceiling</li><li>Domain filters — scope a profile to the domains you choose, so staging headers never reach production</li><li>Pause everything with one click, without losing your configuration</li><li>Reorder headers by dragging them</li><li>Import and export profiles as JSON</li><li>7 languages: English, Español, 日本語, 한국어, Русский, 简体中文, 繁體中文</li></ul>
<strong>Typical uses</strong>
<ul><li>API testing — send <code>Authorization: Bearer &amp;lt;token&gt;</code> to authenticated endpoints</li><li>CORS debugging — add <code>Access-Control-Allow-Origin</code> to reproduce and diagnose</li><li>Environment switching — <code>X-Environment: staging</code> against a different backend</li><li>Device testing — change <code>User-Agent</code> to compare mobile and desktop responses</li></ul>
<strong>Privacy</strong>

No data collection, no analytics, no telemetry, no external servers. Your configurations live in local browser storage and never leave your machine. Header rules are applied by the browser itself through the declarativeNetRequest API — the extension does not read page content, and never sees the requests it modifies.

The full source is on GitHub under the MIT licence. Read it, audit it, fork it.

<strong>Free, and nobody pays for it</strong>

No paywall, no "pro" tier, no nag screens. Nobody funds this work. If you want something improved, open an issue on GitHub and let's talk it through.

Source code: <a href="https://prod.outgoing.prod.webservices.mozgcp.net/v1/703346fd6d1efe8a92b0c5c2dc880705b7cf0f1919a92529945cd109afdd5730/https%3A//github.com/testacode/header-editor-pro-free" rel="nofollow">https://github.com/testacode/header-editor-pro-free</a>

## Rankings

- #41,643 — Overall
- #114 — header
- #127 — editor
- #129 — modify
- #191 — text editor
- #197 — css editor

## Permissions and access

### Permissions

- `declarativeNetRequest`
- `storage`
- `tabGroups`

### Host permissions

- `<all_urls>`

## Safety

- **Risk impact:** Moderate risk impact
- **Risk likelihood:** Moderate risk likelihood

### Analysis details

- Allows access to all websites, posing a significant security risk as it can monitor and modify data from any visited site.
- This extension was recently updated in the past month. New updates may not be stable or safe.

> Some risk analysis details are omitted from this free response. [Upgrade to view the full analysis](https://chrome-stats.com/pricing).

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Source: [Chrome-Stats](https://chrome-stats.com/d/header-editor-pro-free)