Why does Network tab on Developer Tools not allow some headers? (original) (raw)

November 13, 2023, 11:10pm 1

Why can I only edit some headers on Network Tab on Dev tools?

For example I can edit or remove accept header but not Referer as it is grayed out. Why is that functionality nerfed? Isn’t Developer Tools mant for developers? If so what’s the point of limiting them? They could copy it as curl if they wanted, it’s just more annoying.

martijn (Martijn) October 4, 2025, 6:10pm 2

Almost 2y and still no answer to this question

Those are the forbidden request headers ( Forbidden request header - Glossary | MDN )

At the moment, we’re using fetch to resend the request, so we would need something more custom to be able to set those headers.

We have a bug on file to look into this: 983451 - Allow to customize Referer header in Netmonitor
And also 1780171 - Add a (collapsed) section for read-only Headers in Edit-And-Resend to avoid cluttering the UI with these read-only headers

SR_Blinds (SR Blinds) November 24, 2025, 7:37am 4

Hey there!

The simple reason some headers are out is because the browser itself protects them for security and integrity.

If Dev let you instantly change core headers, it could compromise browser security or lead to invalid HTTP requests.

Quick Fix: If you need to test with a custom , your best bet is to Copy the request as URL and edit it in your terminal, or use a third-party extension like Mod Header.