Measure with FingerprintJS Pro

FingerprintJS Pro is the detector Apostate is measured against first. Its public playground shows the verdict for the browser that opens it: a suspect score, and the flags that add to it.

What the playground reports

Field	Meaning	Depends on
`suspect_score`	Sum of the weights of every flag that fired	everything below
`bot`	`not_detected`, `good` or `bad`	the browser and its driver
`tampering`, `tampering_ml_score`	Values that look altered; the model score runs from 0 to 1 and flags above 0.8	the browser
`anti_detect_browser`	Traits of anti-detect browsers	the browser
`anomaly_score`	Values no real browser produces	the browser
`virtual_machine`	Signs of a virtual machine	the browser and the host
`developer_tools`	DevTools open, or a DevTools client attached	the driver
`incognito`	Off-the-record context	how the page was opened
`rare_device`	A combination of values few visitors have	the persona
`vpn`, `proxy`, `timezone_mismatch`	The IP address and its location against the browser’s timezone	the network

A clean browser on a flagged IP address still scores above zero. Read the flags, not only the score.

From the live tier

The live tier loads the playground in every browser it tests and records these fields:

cd tests
python3 -m pytest live --live -k fingerprintjs --personas=windows,macos --controls=chrome

It passes when none of bot, tampering, anti_detect_browser, virtual_machine, developer_tools and incognito is set. Network flags are recorded and do not fail the test. Latest results shows the newest run.

Behind a proxy with measure-fpjs.py

scripts/measure-fpjs.py measures one headed launch through a proxy. It looks up the exit’s country and timezone through the proxy with curl, gives the persona that locale and timezone, loads the playground, and prints every flag.

APOSTATE_PROXY=socks5://user:pass@proxy.example:1080 \
  python3 scripts/measure-fpjs.py --platform windows --seed 42

Option	Default	Effect
`--platform`	`windows`	Persona, or `host` for the real machine
`--seed`	`42`	Seed
`--profile FILE`	none	Launch a profile you wrote instead of a seed
`--window W,H`	`1536,864`	Window size
`--out FILE`	none	Save the playground’s full text
after `--`	none	Extra browser switches

It runs headed, so a Linux server needs Xvfb. Use a fresh proxy session for each run: FingerprintJS remembers a visitor, and a returning visitor with a new machine scores differently from a new one. APOSTATE_BINARY points it at a local build.

Compare fairly

Measure a control on the same exit: --platform host for the real machine, or Google Chrome. Their difference from the persona is what Apostate changes; what they share is the network and the host.
Use the driver your users use. Under plain Playwright, FingerprintJS reports developer_tools on every run; under Patchright, which the packages use, it does not.
Several runs, several seeds. One run is one sample.

​What the playground reports

​From the live tier

​Behind a proxy with measure-fpjs.py

​Compare fairly

What the playground reports

From the live tier

Behind a proxy with measure-fpjs.py

Compare fairly