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Preview of User-Agent Spoofer

User-Agent Spoofer by ThatPrivacyFreak

Spoof the HTTP and JavaScript User-Agent.

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About this extension
User-Agent Spoofer can spoof your HTTP User-Agent and the normal JavaScript navigator User-Agent, but Firefox has one known limitation.

Some websites deliberately create a sandboxed iframe and read its separate navigator object. Firefox can expose the underlying User-Agent from this isolated context even when the normal page's User-Agent has been spoofed.
  • ✅ HTTP User-Agent request header
  • ✅ Normal page navigator.userAgent
  • ✅ Normal page navigator.appVersion
  • ✅ Other supported navigator properties
  • ✅ Custom User-Agent profiles
  • ⚠ Highly isolated/sandboxed iframe User-Agent detection may still reveal the real browser User-Agent.

This is a limitation of Firefox's separate browsing-context behavior rather than a failure of the normal User-Agent spoofing.

Please be aware of this limitation before installing. User-Agent Spoofer does not promise that every browser fingerprinting or anti-spoofing test can be defeated.
There’s an Easter egg hidden inside… can you find it?
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Permissions and data

Required permissions:

  • Access your data for all websites

Data collection:

  • The developer says this extension doesn't require data collection.
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Version
1.0.0
Size
521.27 KB
Last updated
6 days ago (Sep 16, 2026)
Related Categories
  • Privacy & Security
License
GNU General Public License v3.0 only
Version History
  • See all versions
Tags
  • privacy
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