Firefox ResistFingerprinting tester

Various objects in the Navigator object are set to standardised values to prevent fingerprinting. This includes the build IDs, vendor identification and number of logical processors. Test may falsely pass on older versions of Firefox, older computers with weak hardware.

Web Speech API is used to interface with the client’s installed speech synthesis engines (SpeechRecognition is not available on Firefox). Installed TTS dispatcher, voices and other properties can be used for fingerprinting.

Time measurements, like Date.now() or performance.now(), are important for basic time-keeping and benchmarking, but are highly susceptible to fingerprinting. Precise time can reveal differences in system timing settings, synchronisation, CPU frequency scaling and load and many other things, creating a "time fingerprint". Firefox always clamps (rounds) time precision to some extent, though more aggressively when RFP is on.

Performance API provides detailed metrics and high-precision timestamps for measuring performance. Navigation timing, resource timing and millisecond-precise timestamps can be misused for fingerprinting. Even with ResistFingerprinting on, this test will likely fail if dom.enable_performance_navigation_timing is enabled.

Gamepad API is used to detect and interact with gamepads, often used for web games. List of connected gamepads could be used to fingerprint users. This test can only fail if you have any actual gamepads connected (can’t fake those…), otherwise this test will skip itself as "inconclusive".

NetworkInformation API provides information about the client’s network connection, such as its type (wifi, cellular, etc.), bandwidth and other information. API was previously spoofed but now is deprecated (since 2014 on PC and 2022 on Android). This test will fail if available and skip itself if not.