User-Agent Auto Spoofer by Chris Judevine

Per-Site User-Agent Switcher & Spoofer puts you in complete control over how websites perceive your browser and device environment. Instead of forcing a blanket, global identity change that breaks half the web, this extension uses a granular rules system to inject targeted headers and window overrides on a strict per-site basis.

Simply add a domain, assign its target profile, and browse seamlessly.

8 Built-In Profiles Supported:

Desktop Browsers: Firefox Desktop, Google Chrome, Microsoft Edge, Safari Desktop

Mobile Browsers: Android Firefox, Android Chrome, Safari Mobile (iPhone)

Web Crawlers: Googlebot

Key Features:

Set a unique profile for each site or keep it blank to retain your natural browser properties.

Deep Client Spoofing: Seamlessly updates both network request headers (User-Agent) and front-end execution characteristics (navigator.userAgent and navigator.platform).

Privacy-First Design: Fully open-source, uses minimal WebExtension permissions, operates entirely locally on your machine, and never tracks your browsing patterns.

Developer Note on Anti-Fingerprinting: If you are using this to avoid installing a sites app on Android devices, we highly recommend opening advanced settings and manually toggling privacy.resistFingerprinting
Sites such as reddit.com will detect you are using mobile without this enabled. The extension includes a single-click convenience shortcut to copy the configuration URL to your clipboard.