Free browser fingerprint checker and privacy leak tests
Measure what your browser actually gives away — user agent and client hints, canvas and WebGL hashes, audio, fonts, screen, timezone, IP and WebRTC. No account required, no installation, results in a couple of seconds.
You cannot fix what you have not measured
Every website you open receives far more than a request for a page. It receives a User-Agent string and a matching set of client hints, a list of installed fonts, the exact way your GPU rasterises a canvas, the shape of an audio buffer, your screen geometry, your timezone offset, your language preferences and — unless something stops it — the IP addresses your browser is willing to advertise over WebRTC. Put together, those values form a device identity that survives clearing cookies.
That identity is only a problem when it contradicts itself. A profile claiming to be a Windows laptop in Berlin, browsing through a German residential proxy, with a German timezone and German language order, is unremarkable. The same profile with a UTC clock, macOS-only fonts and a WebRTC candidate pointing at your real broadband line is not. Detectors do not need to know who you are; they only need to notice that the story does not hold together.
The tools below let you read every one of those signals before an account depends on them. Run the check on your everyday browser to see your own exposure, then run it again inside a Dual Login profile to confirm the spoofed identity is complete and internally consistent. Test first, then trust the profile with a login — not the other way round.
Start with the full fingerprint report
One page, every signal a commercial detector collects, laid out so you can read it in under a minute.
Browser Fingerprint Checker
The checker reads your browser the same way an anti-fraud script does and prints the raw values back to you, grouped by category, with the ones that most often break a profile highlighted. Nothing is stored: the page reports what the current tab exposes, and a reload gives you a fresh reading you can compare against.
Because the Dual Login engine applies its fingerprint natively in the browser core rather than by injecting JavaScript into the page, what the checker sees inside a profile is exactly what a real site sees — including inside Web Workers, where JavaScript-based spoofing usually falls apart.
Run the fingerprint checkWhat it reports
- User agent, client hints, platform and browser version list
- Canvas, WebGL and audio fingerprint hashes
- GPU vendor and renderer strings
- Installed font list and hardware concurrency
- Screen size, colour depth and device pixel ratio
- Timezone, locale and accept-language order
- Public IP, country and the WebRTC candidate list
The free tool set
Each entry opens a focused view of the same report, so you can jump straight to the signal you are debugging.
Browser Fingerprint Checker
See exactly what your browser reveals — user agent, client hints, canvas and WebGL hashes, audio, fonts, screen, timezone and the WebRTC IP-leak test. Open it inside a Dual Login profile to verify a spoofed identity holds.
WebRTC Leak Test
Confirm your real IP is not escaping past the proxy through WebRTC ICE candidates. Run it in every new profile before you trust an account to it.
Canvas & WebGL Hash Test
Read the canvas and WebGL hashes your profile reports. A healthy result is stable across reloads and different from your other profiles.
User Agent & Client Hints Viewer
Inspect the full UA string and the high-entropy client hints a site can request, and check they agree with the platform you claim to be.
Timezone & Geolocation Check
Verify timezone, locale and the geolocation API all line up with the proxy exit country — a mismatch is one of the easiest tells to spot.
Font & Hardware Profile
Review the font list, CPU cores and device memory your profile advertises, and confirm they are plausible for the device you are presenting.
Automation API Playground
Browse every automation endpoint and copy ready-to-run examples in Python, Node, C#, Java, Go and PHP.
Fingerprinting Explained
A plain-English deep dive into every signal sites collect and how consistent spoofing defeats them.
How to run a proper identity check
A fingerprint check is only meaningful in the environment the account will actually live in. Five steps, in this order, before you log anything in.
- 1
Launch the profile you will actually use
Not a fresh window of your normal browser, and not a temporary profile. Start the exact profile with its assigned proxy attached, let it finish loading, and give the proxy a moment to establish. Testing the wrong window is the most common reason a clean report is followed by a challenged login.
- 2
Open the checker inside that profile
Navigate to the fingerprint checker in the profile window itself. Read the whole report top to bottom once before you start judging individual values — you are looking for a coherent device, not a perfect score on any single line.
- 3
Confirm the IP and ASN match the proxy
The public IP must be the proxy exit, and the ASN should suit the persona: a residential or mobile carrier for consumer accounts, not a datacentre range. If the report shows your own address, the proxy is not being used and nothing below this point matters yet.
- 4
Confirm timezone, locale and geo agree with the IP
The reported timezone should belong to the exit country and show the correct local time, the accept-language order should be plausible for that region, and the geolocation coordinates should sit inside it. In Dual Login these three follow the proxy exit automatically, so this step is a verification rather than a configuration job.
- 5
Check hash stability, then check for a WebRTC leak
Reload the checker two or three times: the canvas, WebGL and audio hashes must stay identical, because a fingerprint that changes on every page view is itself a signal. Then open a second profile side by side and confirm those same hashes differ between them — stable within a profile, unique across profiles is the property you want. Finally, read the WebRTC candidate list. It should contain only the proxy exit address; any candidate carrying your real IP invalidates the entire result, however good the rest of the report looks.
What a clean result looks like
Use this as a checklist while you read the report. Anything in the right-hand column is worth fixing before the profile handles a real account.
| Signal | What to expect | Red flag |
|---|---|---|
| Public IP | The proxy exit address, in the country you configured for the profile. | Your home or office IP, or an address in a different country than the profile. |
| ASN / ISP | A residential or mobile carrier for consumer accounts; a stable ASN across the session. | A hosting or datacentre ASN on a profile that is supposed to be an ordinary shopper. |
| Timezone & clock | An IANA timezone that belongs to the IP's country, with the offset matching local time. | UTC, or your own timezone showing through on a profile with a foreign proxy. |
| Locale & languages | An accept-language list that a real user in that region would send. | en-US on every profile regardless of the exit country, or a language with no regional variant. |
| Canvas & audio hashes | Identical on every reload of the same profile, different from all your other profiles. | A hash that changes on each reload, or one shared by several profiles. |
| WebGL vendor & renderer | A real GPU string that suits the reported platform and screen size. | SwiftShader, a blank renderer, or a mobile GPU on a desktop user agent. |
| WebRTC candidates | Only the proxy exit address; no private range and no real public IP. | Any candidate carrying your true IP, which overrides everything else on this list. |
If several rows fail at once, the fix is usually structural rather than cosmetic — the profile is sharing storage or a proxy with another one. Comparing how different tools approach that isolation is worth a few minutes; our comparison page sets out what to look for.
More free resources
Everything below is open, free and needs no account.
Blog
Field notes on fingerprinting, proxy selection and running multiple accounts without cross-contamination.
Docs
The full API reference: profile management, launch options and every automation action, with request and response samples.
Help centre
Step-by-step guides for installing the app, attaching proxies, importing cookies and inviting your team.
FAQ
Short answers to the questions we get most often about profiles, proxies, plans and platform support.
Turn a clean report into a working profile
The free plan gives you ten isolated profiles, each with its own native fingerprint, its own proxy and its own sealed storage. No credit card, and the checker is right there to prove the identity holds before you use it.
Windows, macOS and Linux — or use the web console at app.duallogin.com.