# ModHeader V1 ✨ by modheader.app ✅

> ModHeader V1 ✨ by modheader.app ✅ Modify change add edit update remove replace override HTTP request and response headers free.

Canonical page: [https://chrome-stats.com/d/modheader-v1](https://chrome-stats.com/d/modheader-v1)

## Overview

- **ID:** `modheader-v1`
- **Platform:** Firefox
- **Type:** Firefox add-on
- **Status:** Removed
- **Publisher:** ModHeader Inc
- **Rating:** 5.00 / 5 (1 ratings)
- **Version:** 2026.8.8.18
- **Last updated:** 2026-08-08
- **First published:** 2026-07-25
- **Size:** 795 KB
- **Data as of:** 2026-08-09
- **Store listing:** [Firefox Add-ons Store](https://addons.mozilla.org/firefox/addon/modheader-v1/)
- **Website:** [https://modheader.app/](https://modheader.app/)

## Description

ModHeader V1 ✨ by modheader.app ✅ – The Ultimate Firefox Add-on for Modifying HTTP Headers

ModHeader V1 ✨ by modheader.app ✅ is a powerful Firefox Add-on for modifying, adding, editing, removing, and overriding HTTP request headers and HTTP response headers. Whether you're a web developer, frontend engineer, backend developer, QA tester, DevOps engineer, security researcher, API developer, or IT professional, ModHeader V1 ✨ by modheader.app ✅ provides an easy way to inspect and customize network requests directly from your browser.

Modify headers without changing your application code. Instantly override User-Agent, Referer, Origin, Cookie, Authorization, Accept, Accept-Language, Cache-Control, Host, X-Forwarded-For, X-Requested-With, Content-Type, Content-Length, Connection, DNT, Sec-Fetch headers, custom headers, and many more.

ModHeader V1 ✨ by modheader.app ✅ is built for modern web development and API testing.

Perfect for Developers.

Key Features:
• Modify HTTP request headers
• Modify HTTP response headers
• Add new request headers
• Add new response headers
• Edit existing headers
• Remove unwanted headers
• Override request headers
• Override response headers
• Replace header values
• Disable headers
• Enable headers with one click
• Create reusable header profiles
• Switch between profiles instantly
• Apply rules based on URL patterns
• Enable or disable rules per website
• Import and export configurations
• Backup and restore profiles
• Lightweight and fast
• Privacy focused
• No unnecessary permissions

Use ModHeader V1 ✨ by modheader.app ✅ to:
• Test REST APIs
• Test GraphQL APIs
• Debug HTTP requests
• Debug HTTP responses
• Simulate different browsers
• Change User-Agent strings
• Override Referer headers
• Modify Origin headers
• Edit Authorization tokens
• Inject Bearer tokens
• Test JWT authentication
• Add API keys
• Modify cookies
• Test CORS behavior
• Debug CORS issues
• Test CDN configurations
• Test reverse proxies
• Test load balancers
• Test cache behavior
• Test localization using Accept-Language
• Test mobile websites
• Test desktop websites
• Test browser compatibility
• Simulate different devices
• Simulate crawlers and bots
• Debug authentication flows
• Test staging environments
• Test production APIs safely

Common Use Cases:
• HTTP header editor
• Request header modifier
• Response header modifier
• Header manager
• User-Agent switcher
• Referer changer
• Cookie editor
• Origin modifier
• Authorization header editor
• API testing tool
• REST API testing
• GraphQL testing
• Network debugging
• Web development
• Frontend development
• Backend development
• Website debugging
• Browser debugging
• CORS testing
• Security testing
• Penetration testing
• QA automation
• Software testing
• Web application testing

Supports Common Headers:
• User-Agent
• Referer
• Origin
• Cookie
• Authorization
• Accept
• Accept-Encoding
• Accept-Language
• Cache-Control
• Pragma
• Connection
• Upgrade-Insecure-Requests
• DNT
• Host
• Content-Type
• Content-Length
• X-Requested-With
• X-Forwarded-For
• X-Real-IP
• X-API-Key
• Custom headers
• Response headers
• Request headers

Why Choose ModHeader V1 ✨ by modheader.app ✅?
• Clean and intuitive interface
• Fast rule matching
• Easy profile management
• Reliable request interception
• Powerful header modification engine
• Designed for developers
• Works with modern websites
• Regular updates
• High performance
• Easy to learn
• Advanced features for professionals

Whether you're debugging an API, testing authentication, modifying request headers, overriding response headers, changing User-Agent, editing cookies, troubleshooting CORS, or building modern web applications, ModHeader V1 ✨ by modheader.app ✅ is the Firefox Add-on that helps you work faster and more efficiently.

## Permissions and access

### Permissions

- `clipboardRead`
- `clipboardWrite`
- `declarativeNetRequest`
- `storage`

### Host permissions

- `<all_urls>`

## Safety

- **Risk impact:** Moderate risk impact
- **Risk likelihood:** High 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 is not longer available in the store

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

## Similar extensions and apps

- [ModHeader V2 ✨ by modheader.app ✅](https://chrome-stats.com/d/modheader-v2) — 8 users, 5.00 / 5
- [ModHeader ✨ by modheader.app ✅](https://chrome-stats.com/d/modheader-by-modheader-app) — 229 users, 5.00 / 5
- [ModHeader V5 ✨ by modheader.app ✅](https://chrome-stats.com/d/modheader-v5) — 2 users, 5.00 / 5
- [ModHeader V3 ✨ by modheader.app ✅](https://chrome-stats.com/d/modheader-v3) — 3 users, 5.00 / 5
- [ModHeader V4 ✨ by modheader.app ✅](https://chrome-stats.com/d/modheader-v4) — 1 users, 5.00 / 5
- [ModHeader V6 ✨ by modheader.app ✅](https://chrome-stats.com/d/modheader-v6) — 21 users, 5.00 / 5
- [ModHeader Pro ✨ by modheader.app ✅](https://chrome-stats.com/d/modheader-pro) — 1 users, 5.00 / 5
- [ModHeader Premium ✨ by modheader.app ✅](https://chrome-stats.com/d/modheader-premium) — 1 users, 5.00 / 5
- [ModHeader Plus ✨ by modheader.app ✅](https://chrome-stats.com/d/modheader-plus) — 1 users, 5.00 / 5
- [Modify Header Value](https://chrome-stats.com/d/modify-header-value) — 9,551 users, 3.62 / 5
- [ModHeader](https://chrome-stats.com/d/modheader-firefox) — 19,864 users, 3.37 / 5
- [HeaderMod](https://chrome-stats.com/d/headermod) — 292 users

---

Source: [Chrome-Stats](https://chrome-stats.com/d/modheader-v1)