Add xHeader to Chrome
Add xHeader to Firefox
Request and response headers
Add, change, or remove the HTTP headers involved in the browser requests you are testing.
Chrome and Firefox extension for developers
Control every header.
Unblock CORS testing.
xHeader is a clean ModHeader alternative with no malware, spyware, or ads. Modify HTTP request and response headers in Chrome or Firefox, unblock browser-based CORS testing, build profiles, and iterate safely with advanced filters, undo, redo, and autocomplete.
Explore all features
xHeader
Header rules for this profile
Active
Local API Staging QA +
Request header
Authorization Bearer •••••••••••• Response header
Access-Control-Allow-Origin http://localhost:3000 Filter: *://api.example.com/* ↶ ↷
Developer workflow
Header testing without the busywork
Unblock CORS testing, organize repeatable setups, target rules precisely, and recover instantly while you experiment.
Multiple profiles
Keep separate header setups for local development, staging, QA, and different projects.
Advanced filters
Target the traffic that matters instead of applying every rule to every request.
Undo and redo
Experiment quickly and recover from changes without rebuilding your configuration.
Header autocomplete
Spend less time recalling header names and more time testing the behavior you care about.
A clean ModHeader alternative
No malware, spyware, or ads—just a focused workflow for modifying headers in Chrome and Firefox.
Built for real testing
From one-off checks to repeatable QA
Use xHeader anywhere a controlled browser header can shorten the feedback loop.
01
API development
Test authentication and custom headers
Try Authorization, content negotiation, feature flags, and custom X-* headers without changing application code for every test.
02
CORS debugging
Unblock browser-based CORS testing
Modify relevant request and response headers in your own browser session so CORS errors do not stop local development and QA.
03
Frontend QA
Switch environments with profiles
Keep repeatable configurations for development, staging, and QA, then move between them as your test plan changes.
Choose the right layer
xHeader and CORSPROXY solve different jobs
Use the browser extension for your own test session. Use a proxy service when your application needs a production-ready server-side request path.
Use xHeader
- ✓Modify headers in your browser
- ✓Debug and test local or staging behavior
- ✓Maintain multiple personal testing profiles
- ✓Fetch remote resources server-side
- ✓Return responses your web application can consume
- ✓Support application traffic beyond one browser
FAQ
Questions about xHeader
What is xHeader?
xHeader is a Chrome and Firefox extension for modifying HTTP request and response headers. It is designed for developers, testers, and other technical users who need controlled header changes in the browser.
Is xHeader an alternative to ModHeader?
Yes. xHeader is a clean ModHeader alternative with no malware, spyware, or ads. It covers the core header-modification workflow while adding multiple profiles, advanced filters, undo and redo, and autocomplete.
Can xHeader help debug CORS issues?
Yes. xHeader can unblock browser-based CORS testing by modifying relevant request and response headers in your own development session. A browser extension is not a production CORS architecture and does not change what other users' browsers receive.
When should I use CORSPROXY instead?
Use CORSPROXY when an application needs a server-side request path that fetches a remote resource and returns a browser-compatible response. Use xHeader when you need to modify headers inside your own Chrome testing session.
Make headers work your way
Install xHeader and move faster through API development, unblocked CORS testing, and browser-based QA.