# UA Intercept

> Switch your User-Agent with named profiles. Pick a preset, append or replace UA tokens, and choose the spoof depth: headers only, or a full override page JavaScript sees too. Imports ModHeader profiles. No ads, no tracking, open source.

Canonical page: [https://chrome-stats.com/d/ua-intercept](https://chrome-stats.com/d/ua-intercept)

## Overview

- **ID:** `ua-intercept`
- **Platform:** Firefox
- **Type:** Firefox add-on
- **Status:** Available
- **Publisher:** sizzlor
- **Category:** web-development,privacy-security
- **Daily users:** 3
- **Weekly downloads:** 1
- **Version:** 0.1.3
- **Last updated:** 2026-07-20
- **First published:** 2026-07-14
- **Size:** 80 KB
- **Data as of:** 2026-09-09
- **Store listing:** [Firefox Add-ons Store](https://addons.mozilla.org/firefox/addon/ua-intercept/)
- **Website:** [https://github.com/sizzlorox/ua-intercept/issues](https://github.com/sizzlorox/ua-intercept/issues)
- **Privacy policy:** [https://addons.mozilla.org/firefox/addon/ua-intercept/privacy/](https://addons.mozilla.org/firefox/addon/ua-intercept/privacy/)

## Description

<strong>UA Intercept does one thing well: it changes your User-Agent.</strong>

Not a generic header editor — a User-Agent switcher with named profiles, a preset picker, and a spoof depth you choose.

<ul><li><strong>Profiles</strong> — create, edit, duplicate, and delete named User-Agent profiles; one active at a time, switchable from the toolbar popup.</li><li><strong>UA tokens</strong> — build a User-Agent from tokens you can enable individually and either <em>append</em> to your real User-Agent or <em>replace</em> it outright.</li><li><strong>Selectable spoof depth</strong> — <em>Headers only</em> changes just the <code>User-Agent</code> request header the server sees. <em>Full</em> also sets matching <code>sec-ch-ua*</code> Client Hints and rewrites <code>navigator.userAgent</code>, <code>navigator.platform</code>, <code>navigator.userAgentData</code>, <code>navigator.appVersion</code>, and <code>navigator.vendor</code> so page JavaScript sees the override too.</li><li><strong>Preset picker</strong> — Windows/macOS/Android Chrome, macOS/iOS/iPadOS Safari, Linux Firefox, Googlebot, or a fully custom User-Agent.</li><li><strong>Import / export</strong> — versioned JSON of your own, plus best-effort import of <strong>ModHeader</strong> exports (every User-Agent row, enabled or disabled, with its URL filters).</li><li><strong>Per-profile URL filters</strong> — scope a profile to, or away from, specific domains.</li><li><strong>20 languages</strong> with RTL support, a toolbar badge while active, and a keyboard-operable, screen-reader-labeled UI.</li></ul>

No data collection, no telemetry, no ads, no account. Profiles never leave your device. The only network request is an opt-in, <strong>off-by-default</strong> update check against GitHub's public Releases API, which sends none of your data.

This is not a stealth tool — full spoof defeats casual User-Agent sniffing, not a determined fingerprinter. Web Workers are not covered by the full spoof, and the override is detectable by page JavaScript.

Open source (MIT): <a href="https://prod.outgoing.prod.webservices.mozgcp.net/v1/d030f215183f8d8823305a76f84e68a4992d54153ca70dfaff2e376282cbd31a/https%3A//github.com/sizzlorox/ua-intercept" rel="nofollow">https://github.com/sizzlorox/ua-intercept</a>

## Rankings

- #54,768 — Overall
- #27 — modheader
- #175 — override

## Permissions and access

### Permissions

- `declarativeNetRequestWithHostAccess`
- `scripting`
- `storage`

### Host permissions

- `<all_urls>`

## Safety

- **Risk impact:** Moderate risk impact
- **Risk likelihood:** High 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 has low user count. Unpopular extensions 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/ua-intercept)