UA Intercept

Name: UA Intercept
Author: sizzlor

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.

Overview

Firefox Add-ons Store

Daily users

Data as of 2026-07-28

Version:

0.1.3

Last updated: 2026-07-20

Features & Capabilities

UA Intercept does one thing well: it changes your User-Agent.

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

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

No data collection, no telemetry, no ads, no account. Profiles never leave your device. The only network request is an opt-in, off-by-default 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): https://github.com/sizzlorox/ua-intercept

User Growth & Download Statistics

Add-on

By:

sizzlor

Daily users:

Version:

0.1.3 Last updated: 2026-07-20

Version code:

6364576

Creation date:

2026-07-14

Risk:

Permissions:

declarativeNetRequestWithHostAccess
scripting
storage

Host permissions:

<all_urls>

Size:

80.49KB

URLs:

Website ,Privacy policy

Full description:

Source:

Firefox Add-ons Store

Data ingested on:

2026-07-28

Compare stats and ranking:

Ranking

# 95,012 ▲ 564

Other rankings

#38 in modheader keyword 25 ▼ 11#238 in override keyword 10 ▼ 6

For Developers

Monetize with App Pass Boost with Extension Booster

Contact the developer

Chrome-Stats does not own this Firefox add-on. Please use these information below to contact the Firefox add-on developer.

Developed by:

sizzlor

Firefox Add-ons Store

https://addons.mozilla.org/firefox/addon/ua-intercept/

Website:

https://github.com/sizzlorox/ua-intercept/issues

Is UA Intercept Safe?

Risk impact

Risk impact measures the level of extra permissions an extension has access to. A low risk impact extension cannot do much harms, whereas a high risk impact extension can do a lot of damage like stealing your password, bypassing your security settings, and accessing your personal data. High risk impact extensions are not necessarily malicious. However, if they do turn malicious, they can be very harmful.

UA Intercept requires a few sensitive permissions. Exercise caution before installing.

Risk impact analysis details

Critical Allows access to all websites, posing a significant security risk as it can monitor and modify data from any visited site.

Risk likelihood

Risk likelihood measures the probability that a Firefox add-on may turn malicious. This is determined by the publisher and the Firefox add-on reputation on Firefox Add-ons Store, the amount of time the Firefox add-on has been around, and other signals about the Firefox add-on. Our algorithms are not perfect, and are subject to change as we discover new ways to detect malicious extensions. We recommend that you always exercise caution when installing a Firefox add-on.

UA Intercept is recently added, and hasn't been around long enough for us to gather enough data to accurately assess its risk level.

Risk likelihood analysis details

High This extension was recently updated in the past month. New updates may not be stable or safe.
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