Edit request and response headers
Set, append, or remove a header from the popup. Authorization, feature flags, or X-Forwarded-For — without changing app code.
Request headers
AuthorizationBearer test
Modify HTTP request and response headers
MockHeader is a free, open-source extension for editing HTTP request and response headers. No sign-up. Install it, change a header, and test without touching your app code.
Open source. Rules stay on this device.
How it works
- 1Install the extensionLoad MockHeader unpacked from GitHub. Free. No account.
- 2Add or modify headersOpen the popup and set request headers, response headers, cookies, and redirects.
- 3Toggle and debugTurn rules on or off. URL, tab, and resource filters keep changes limited to what you want.
Features
Toggle rules with one click
Enable or disable modifications while you test. Same page, feature on in one pass and off in the next.
X-MockHeader-Test
X-Frame-Options
Filter by URL, tab, or resource
Apply rules only on matching URLs, tabs, windows, or resource types so tokens do not leak to other sites.
Includeexample.com
Page · Host · Domain
Profiles and redirects
Keep separate profiles for projects. Wildcard or regex redirects. Export and import when you need to share a setup.
from*://httpbin.org/get
tohttps://example.com/
FAQs
How do I modify a request header?
Open the popup. Enter the header name (for example Authorization) and its value, then leave the rule enabled. Matching requests pick it up right away.
Can I limit modifications to certain URLs or tabs?
Yes. URL, tab, window, and resource type filters limit where rules apply, which helps keep tokens off sites you did not mean to touch.
Is MockHeader free? Which browsers are supported?
Yes. MockHeader is free and open source. There is no account. Chrome is supported today; load unpacked from GitHub until the store listing is live.
Does MockHeader collect or sell my data?
No. Profiles stay in chrome.storage on this device. See the Privacy Policy.
Load unpacked
bun install && bun run buildchrome://extensions → Developer mode → Load unpacked → output/chrome-mv3.