Fingerprint isolation test: a practical browser profile checklist
Test cookies, login state, browser-exposed settings and proxy routing across isolated profiles without treating different values as proof of anonymity.
What does this test prove?
A fingerprint isolation test should answer three narrow questions: does each profile keep its own site data, does a saved profile reproduce its intended browser configuration, and does traffic use the expected network route? Passing these checks shows that the tested boundaries work in that setup. It does not prove anonymity, account safety or acceptance by a third-party platform.
This checklist was reviewed October 2, 2026 against the documented IFox9 0.0.3 desktop release and Chromium 152 kernel.
Prepare two disposable profiles
- Create Test A and Test B with names that cannot be confused with production profiles.
- Do not sign in to a sensitive store, advertising or payment account.
- If network separation is part of the test, assign the intended proxy to each profile before opening a page.
- Record the app version, browser-kernel version, operating system and test time.
Using disposable profiles makes the result repeatable and prevents a diagnostic check from changing a live account session.
Check storage and login-state separation
- In Test A, open a harmless site that can store a preference or test cookie.
- Set the preference, close the profile and reopen it. Confirm that Test A retains the expected state.
- Open the same site in Test B. Confirm that the Test A preference, cookie and signed-in state are absent.
- Repeat once after restarting IFox9.
If state appears in both profiles, stop using the profiles for separate accounts and collect the minimum reproducible steps for support.
Inspect the browser-exposed configuration
| Field | Expected result |
|---|---|
| User agent and platform | They describe the saved operating-system and browser combination. |
| Screen and hardware | Resolution, CPU and memory-related values remain consistent with the selected profile. |
| WebGL and WebGPU | Renderer and feature mode agree with the selected platform and GPU configuration. |
| Canvas, audio and related noise | Enabled settings remain stable for the saved profile across relaunches. |
| Language and time zone | Values match the intended region and do not contradict the network route. |
| WebRTC | The observed mode matches the saved choice and does not unexpectedly expose another route. |
Verify the network separately
Profile data can be isolated while two profiles still use the same public IP. Record the visible IP and region for each profile, then compare them with the assigned proxy. If time zone uses IP-based detection, verify that the resolved time zone matches the proxy region. A failed proxy check is a network problem, not evidence that cookies crossed between profiles.
Use the proxy and fingerprint consistency guide when IP, time zone, language or WebRTC values disagree.
Test persistence, then change one variable
Close and reopen Test A twice and compare the recorded values. A saved profile should remain consistent across those runs. When investigating a mismatch, change only one setting and repeat the same observation. Re-randomizing every field destroys the baseline and makes the cause impossible to isolate.
Record a pass, fail or limitation
- Pass: saved state returns in the same profile, does not appear in the second profile, and the intended route is visible.
- Fail: state crosses profiles, the saved configuration does not reload, or the route differs from the configured proxy.
- Limitation: a diagnostic page cannot observe the signal, or a third-party test reports a result without explaining its method.
Keep screenshots free of account credentials. For product support, include versions and reproducible steps, not passwords, cookies or access tokens.
Continue with the isolation guide
Read browser profile isolation for the complete model, or compare saved profiles with incognito mode and proxies. When the test profile is stable, follow the MCP quickstart with a read-only browser task.