ModHeader ✨ by modheader.app ✅ per ModHeader Inc

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

ModHeader ✨ 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 ✨ 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 ✨ 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 ✨ 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 ✨ 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 ✨ by modheader.app ✅ is the Firefox Add-on that helps you work faster and more efficiently.