Checking your own setup

A check asks your browser questions and prints the answers. Every row belongs to your machine rather than to the page asking.

None of it is a decision. A platform decides from the same answers plus what it knows about your other accounts, and publishes neither.

• The values

  Screen, graphics card, fonts, clock, languages, and the drawings your machine makes.

• What goes out unasked

  The addresses the browser hands to any site by itself, with nothing asked of it.

• The exit

  The address a site sees, which is the proxy's only while the proxy carries traffic.

• Not your other profiles

  One page sees one browser, and the linking signal lives between two of them.

An outside checker weighs its rows the way its author chose and prints a number. Another checker on the same browser prints a different one.

So the number describes the checker. The rows underneath describe your machine, and only those are worth reading twice.

Each step answers something the one before it cannot. Run all of them inside the profile you are checking.

• Read the values

  Open the free check in the profile and start with the rows marked as telling you apart.

• Ask about leaks

  The leak test shows which addresses the browser gives out itself, and a proxy has no say there.

• Compare your own profiles

  Take the short code the check prints in each profile and count the repeats.

• Then an outside checker

  The profile start page keeps links to the ones this trade uses, opened through the profile's own proxy.

A single odd value rarely gets an account looked at. A pair of values that cannot both be true does.

This is what a check is good at: it holds one set of answers next to itself and shows where the set argues.

Most rows repeat what any page could show you. A few are what actually separates one browser from the next, and a good check marks those.

They are the picture and the tone your machine produces, the pixels the card returns, the fonts, the screen, the clock and the languages.

A card's name is easy to change and the pixels behind it are not, which is why the two sit in separate rows.

The app runs an audit of its own, and it does what no outside page can: it knows what the profile promised, so it can name the value that disagrees.

A desktop profile of the current generation runs 29 checks in a throwaway copy carrying the same seed, and your open session is left alone.

• The values

  Platform, the system it reports, screen, cores, memory, graphics renderer, clock and the languages.

• The hiding

  A patched function that no longer reads as native code proves tampering more plainly than a mismatch.

• Frames and threads

  A hidden frame and a background thread have to answer the same cores and system as the document.

• The drawings

  Two reads agree, transparent pixels stay transparent, and the noise resists subtraction.

Some rows read red on a perfectly correct profile, and knowing which ones saves you from repairing what works.

• The canonical zone name

  A Kyiv clock answers as Europe/Kiev and a Kolkata one as Asia/Calcutta, as an ordinary Chrome does.

• The capped memory

  Chrome reports memory only up to a ceiling of its own, whatever the machine holds.

• A phone's fonts on a computer

  The fonts a phone profile claims live on Android and almost nowhere else.

A check that cannot measure says so rather than printing a reassuring line. An invented pass is worse than no answer, because you act on it.

So the start page gives no verdict on the proxy while your own address is unknown, and the self-test declines to run when it cannot prepare its throwaway copy.