What does AddHeader do?

AddHeader focuses on adding custom HTTP headers to all requests or requests for selected websites. It is catalogued under Browser DevTools & extensions on PulseGate.

Who is AddHeader for?

AddHeader is a consumer product built for firefox users and web developers testing or modifying HTTP requests.

Does AddHeader have a free plan?

Yes — AddHeader is free to use.

What platforms does AddHeader run on?

AddHeader runs on the web, embeddable surfaces, macOS, Windows, and Linux.

Is AddHeader still active?

Unverified. AddHeader has not been re-checked since it entered the index, so there is no finding either way — and only a positive finding would say otherwise.

What are alternatives to AddHeader?

Similar projects tracked by PulseGate include Modify HTTP Headers, Request Header Modifier, and Mozilla Custom Headers.

Who develops AddHeader?

AddHeader is developed by Firefox user 13564830.

How long has AddHeader been around?

AddHeader first shipped in 2017.

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AddHeader

Name: AddHeader
Author: Firefox user 13564830

mozilla.orgBrowser DevTools & extensions

AddHeader is a Firefox browser extension that adds custom or dummy HTTP headers and values to web requests. Users can apply headers globally or restrict them to requests for specific websites, making it useful for web development and testing.

FreeWebEmbeddablemacOSWindowsLinux

Visit mozilla.org

Overview

6 features

AddHeader sits in PulseGate's Browser DevTools & extensions category. It focuses on adding custom HTTP headers to all requests or requests for selected websites. It is built as a consumer product for firefox users and web developers testing or modifying HTTP requests. AddHeader is free to use. It ships for the web, embeddable surfaces, macOS, Windows, and Linux.

Behind AddHeader is Firefox user 13564830, and it first shipped in 2017. Among its 6 catalogued features are custom headers, dummy header values, and global request rules. The interface is available in 32 languages, including Czech, German, and Greek.

Summary written by a language model from the project’s public pages.

Custom headers
Dummy header values
Global request rules
Site-specific rules
HTTP request modification
Firefox integration

Built with & integrations

Runs on

BrowserEmbeddablemacOSWindowsLinux

Trust & compliance

Verified signals

HTTPSPrivacy Policy Terms of ServiceFree tierMulti-languageStore-verified publisher

Legal

Indexing history

What PulseGate has recorded for this listing

Indexed12 Sep · 02:33 UTC
AddHeader verified via Firefox Add-ons
Source: Firefox Add-ons · Open

Frequently asked questions about AddHeader

What does AddHeader do?: AddHeader focuses on adding custom HTTP headers to all requests or requests for selected websites. It is catalogued under Browser DevTools & extensions on PulseGate.
Who is AddHeader for?: AddHeader is a consumer product built for firefox users and web developers testing or modifying HTTP requests.
Does AddHeader have a free plan?: Yes — AddHeader is free to use.
What platforms does AddHeader run on?: AddHeader runs on the web, embeddable surfaces, macOS, Windows, and Linux.
Is AddHeader still active?: Unverified. AddHeader has not been re-checked since it entered the index, so there is no finding either way — and only a positive finding would say otherwise.
What are alternatives to AddHeader?: Similar projects tracked by PulseGate include Modify HTTP Headers, Request Header Modifier, and Mozilla Custom Headers.Modify HTTP Headers Request Header Modifier Mozilla Custom Headers
Who develops AddHeader?: AddHeader is developed by Firefox user 13564830.
How long has AddHeader been around?: AddHeader first shipped in 2017.

At a glance

Pricing: Free
Platforms: Web
First seen: 12 Sep 2026
Built for: Firefox users and web developers testing or modifying HTTP requests
Model: B2C
Solves: Adding custom HTTP headers to all requests or requests for selected websites.

Registered as

Firefox Add-ons: addheader

Developer

Firefox user 13564830

Index record

Indexed: 12 Sep 2026
Lifecycle: Alive
First seen: Sep 2026
Last seen: 12 Sep 2026

Identity audit (13)

Slug: addheader-mozilla-org
Lifecycle state recorded: 12 Sep 2026
Verification state: Indexed for public listing
Listing state: Listed: yes
Index status: Included in index
Latest evidence snapshot: 12 Sep 2026
Timeline basis: Indexed-at chronology (no inferred launch/funding milestones).
Name from: Derived from the project's own page and URL.
Category from: Assigned by a language model.
Summary from: Written by a language model from public pages.
Languages from: Detected by a language model, checked against the page's own declaration.
Last updated: 12 Sep 2026
Canonical URL: https://addons.mozilla.org/en-US/firefox/addon/addheader

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