Clearing cookies and using private windows will not stop trackers that read your browser’s settings and hardware. Here is how fingerprinting works, why it survives a cleanup, and what you can change.
This guide is general information, not technical or legal advice. If you’ve lost money or personal information, contact your bank, IDCARE on 1800 595 160, or report it through ReportCyber at cyber.gov.au.
Quick summary
- Browser fingerprinting identifies you from your settings and hardware rather than stored files, so clearing cookies or using a private window does not remove it.
- Trackers combine small details such as screen resolution, time zone, installed fonts and battery level into a profile unique to your device.
- Browsers usually convey between 5 and 15 bits of identifying information, and user agent strings alone averaged about 10.5 bits in an EFF experiment.
- Resetting your phone’s advertising identifier, declining tracking prompts and turning off ad personalisation reduce what trackers can learn about you.
- Protections do not need to be perfect to help, but unusual privacy settings can make your browser stand out more, not less.
Clearing cookies, using a private window and refusing permission prompts all feel like solid privacy habits, yet advertising trackers can still follow you from site to site. Many no longer depend on files stored on your device. They read your browser instead, gathering small details about your settings and hardware and stitching them into a profile known as a browser fingerprint. Here is how it works.
What Browser Fingerprinting Actually Is
When you open a website, your browser requests that page. In the background, advertising code and invisible trackers can push your browser to make dozens or even hundreds of further requests to hidden third parties. Each request carries information about you, from your time zone to your browser settings and installed software versions. Some of it is passed along so the page displays properly; tracking scripts extract the rest.
A digital fingerprint is that list of characteristics stitched together into a picture unique to your browser and hardware. Usually it is a third-party tracking company, not the site you visited, doing the collecting. Because the same tracker appears on many sites and apps, it can follow your activity across all of them.
The Clues Your Browser Gives Away
The details seem harmless one at a time: screen resolution, time zone, operating system version, installed fonts, even remaining battery life. Your browser also broadcasts a user agent string naming the browser, its version and your operating system. Some characteristics, such as the canvas fingerprint, are measured by running small pieces of JavaScript on the page.
Each detail narrows the crowd you sit in. Browsers usually convey between 5 and 15 bits of identifying information, and in an Electronic Frontier Foundation experiment the user agent string alone averaged about 10.5 bits, roughly one-third of the information needed to single a person out.
Illustration only: imagine a tracker noting a browser in the Australia/Sydney time zone, at an uncommon screen resolution, with a distinctive set of fonts and a less popular browser version. Thousands of people match each detail on its own, but combined, the profile fits one person who can then be recognised on the next site without any file being stored.
Fingerprinting vs Cookies: Why Clearing Cookies Doesn’t Help
Cookies are files a website asks your browser to store, and you can delete or refuse them in your settings. Fingerprinting works differently: instead of handing you an identifier, the tracker summarises characteristics that are harder to change and often impossible to delete, such as hardware specifications and browser settings. It is closer to recognising a bird by its song than by a leg band.
That is why private browsing windows do not help much. Stored identifiers usually stay out of private sessions, but a fingerprint reads the machine and settings themselves, which look the same either way. Clearing browser data is still worthwhile, yet it leaves the fingerprint untouched.
Who Uses Fingerprints, and For What
Tracking companies use fingerprints to target advertising and recognise returning visitors, showing ads based on your previous browsing, a practice called retargeting. Some sell the resulting profiles to data brokers, and digital advertising is a business worth hundreds of billions of dollars. Companies can also connect your identity across devices, linking what you do on a laptop with what you do on a phone and tailoring ads to both.
Not every use is commercial. The same technology helps detect fraud and bots, and services use similar signals to make it harder for attackers to use stolen accounts.
What You Can Do to Stand Out Less
You cannot delete a fingerprint the way you delete a cookie, but you can shrink what it reveals. On a phone, look in the privacy settings for an option to reset your advertising identifier, decline prompts asking an app to track your activity, and turn off ad personalisation. Settings changed on one device or browser do not carry over to the others, so check each one.
Some browsers protect their users by making every copy look identical to websites, regardless of the computer it runs on. There is strength in numbers: if many people present the same fingerprint, nobody stands out. Tracker-blocking extensions help too, and protections do not need to be perfect to make a real difference. Our checklist covers what to weigh up before you install a browser extension.
Two trade-offs deserve a mention. Turning off JavaScript stops many tracking scripts but also breaks shopping carts, forms and video on plenty of sites. And unusually strict privacy settings can make your browser more distinctive, because fewer people share your exact configuration.
Handy tip
The Electronic Frontier Foundation offers a free tool called Cover Your Tracks that shows how visible your browser is to trackers and whether your fingerprint stands out from the crowd.
When Fingerprinting Is Useful Instead of Creepy
The same identification techniques have ordinary uses. A site can remember your preferences without a login, and fraud detection depends on spotting when a device suddenly behaves unlike its owner. Bot detection uses these signals to keep automated traffic from masquerading as real visitors. The problem is not the technique itself but how widely it is applied without consent, and that ordinary browser controls cannot simply switch it off.
Questions Worth Asking Before You Install Anti-Fingerprinting Tools
Before installing a tool that resists fingerprinting, ask a few questions. Will it break parts of websites you rely on? Will its unusual settings make your browser rarer, and therefore easier to single out? Does the developer explain plainly what it does and does not protect against, given that tracking techniques keep changing?
Fingerprinting is not only a browser problem, either. Apps on your phone can gather identifying details about the device itself, and web services profile you through your account data. Reviewing the privacy settings of the services you use, including AI chatbots, closes some of those gaps.
A concrete next step: open your phone’s privacy settings, reset the advertising identifier and switch off ad personalisation, then repeat the exercise on your other devices and browsers.
Your questions answered
Q: Does private browsing stop fingerprinting?
A: No. Private windows clear stored files, but your hardware, screen resolution and browser settings look the same in any mode, so the fingerprint stays intact.
Q: How can I tell how visible my browser is?
A: The Electronic Frontier Foundation’s free Cover Your Tracks tool tests your browser and reports whether your fingerprint stands out, along with how well your tracking protections are working.
Q: Is browser fingerprinting legal in Australia?
A: The rules on collecting and using personal information depend on where you live and how the data is handled, and the practice is contested worldwide. Whatever the law says, the practical defences are the same: reduce what your browser and apps reveal.
Q: Should I install an anti-fingerprinting extension?
A: Possibly, but check first whether it will break sites you use and whether its uncommon settings make you more distinctive. Work through a checklist for browser extensions before adding any new one.