# FlexHeaders - Modify HTTP Headers

> A lightweight yet powerful extension to modify HTTP headers on the fly. Unleash the power of FlexHeaders, the ultimate extension for developers and security-conscious users

Canonical page: [https://chrome-stats.com/d/flexheaders-alter-http-headers](https://chrome-stats.com/d/flexheaders-alter-http-headers)

## Overview

- **ID:** `flexheaders-alter-http-headers`
- **Platform:** Firefox
- **Type:** Firefox add-on
- **Status:** Available
- **Publisher:** Harrison Deo
- **Category:** web-development
- **Daily users:** 471
- **Weekly downloads:** 31
- **Rating:** 5.00 / 5 (2 ratings)
- **Version:** 1.11.0
- **Last updated:** 2026-08-22
- **First published:** 2024-09-25
- **Size:** 195 KB
- **Data as of:** 2026-09-06
- **Store listing:** [Firefox Add-ons Store](https://addons.mozilla.org/firefox/addon/flexheaders-alter-http-headers/)
- **Website:** [https://www.harrisondeo.me.uk/flex-header](https://www.harrisondeo.me.uk/flex-header)

## Description

**FlexHeaders** is a lightweight yet powerful Chrome extension designed for developers and security-conscious users who want to modify HTTP headers effortlessly. It empowers you to take full control over your browsing experience by customizing request headers with precision — from tweaking user agents to adding custom headers.

Key features include URL filtering that applies modifications to specific sites, preset import/export for team workflows, and a user-friendly interface requiring no coding skills. As an open-source tool, FlexHeaders invites contributions and transparency. Strengthen your online security, enhance privacy, and shape your web interactions like a pro with FlexHeaders.

## Rankings

- #5,231 — Overall
- #6 — modheader
- #6 — modify
- #19 — header
- #142 — lead
- #167 — development

## Permissions and access

### Permissions

- `storage`
- `declarativeNetRequest`

### Host permissions

- `<all_urls>`

## Safety

- **Risk impact:** Moderate risk impact
- **Risk likelihood:** Moderate risk likelihood

### Analysis details

- Allows access to all websites, posing a significant security risk as it can monitor and modify data from any visited site.
- This extension was recently updated in the past month. New updates may not be stable or safe.

> Some risk analysis details are omitted from this free response. [Upgrade to view the full analysis](https://chrome-stats.com/pricing).

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Source: [Chrome-Stats](https://chrome-stats.com/d/flexheaders-alter-http-headers)