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Response and request headers

note

Request headers are only available on paid plans. Check our plans here.

You can modify both request and response headers. You can specify:

  • The header name (Key column)
  • The header value (Value column)

headers table editor in tweak

info

HTTP header names are case-insensitive (web standard) and some header names are forbidden.

Forbidden names are flagged in red here, because mock and modify rules go through fetch and XHR, which the browser does not let set them. A headers only rule is applied by the browser itself, so it can set them: switch the rule type and the row will apply.

Additional features​

You can use variables in the headers' tables. When you use a variable in the table, it will be highlighted. You can hover on them to reveal their value.

tip

A few more tips:

  1. You can use "Request hook" to modify request headers programmatically with JavaScript.
  2. Setting Content-Type: text/event-stream or Transfer-Encoding: chunked mocks a streaming response. Combine this with the delay field to control the time between chunks.

Modifying only headers?​

If the headers are the only thing you want to change, a headers only rule is the better fit: it leaves the payload untouched, it's more robust, adds append and remove operations, and reaches requests your JavaScript never makes (page navigations, scripts, images, stylesheets).


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