Yellow Dots of Mystery: Is Your Printer Spying on You?


Imagine that every time you print a document, it automatically includes a secret code that could be used to identify the printer -- and, potentially, the person who used it. Sounds like something from a spy movie, right?

Unfortunately, the scenario isn't fictional. Most color laser printers and color copiers are designed to print invisible tracking codes across every single printed page of their output. These codes reveal which machine produced a document and, in some cases, when the document was printed or copied.

In this instructable, we'll describe three different ways to see the tracking dots your printer produces: with a blue light, with a microscope, or with a scanner. If you don't have the necessary equipment for a particular step, go on to the next one.

For further information, or to share your findings, please visit us at

Want to help? Download test sheets at
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Step 1: Print a page with text/graphics

Picture of Print a page with text/graphics

Print out a page from a color laser printer. The page should use color and have some text or graphics on it. You can find a list of printers that we know print tracking dots at our website.

As you're looking for the dots, keep in mind that they're printed in a regularly repeating pattern across the entire page (not just in the corner of the page), and will be intermixed with other printed data.

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paverphalange3 months ago

his is wrong in so many ways and quite disturbing as well come to think of it...

motherprune4 months ago

Thats sweet

cobbledbeard4 months ago

his is wrong in so many ways and quite disturbing as well come to think of it...

mousepaper4 months ago

Its fabulous :)

Its nice

amazedgreen4 months ago

Thats remarkable

fastbobble4 months ago

Thats astounding

gorgeddamp4 months ago

Thats astounding

clearedeager4 months ago

Its extraordinary

illrings5 months ago

Thats cold

airbugger5 months ago


Its extraordinary

headlymph5 months ago


tealrink5 months ago


grousebandit5 months ago

Thats magnificent...

harechubby5 months ago


jiffymanager6 months ago


calmlunch6 months ago


spewlocks6 months ago


clapfilk6 months ago



spongeraffle6 months ago

Its nice

workexaminer6 months ago

Thats hip

bearblue8 months ago


bearblue8 months ago


gazumpglue8 months ago

Very weird and strange.

Very weird and strange.
BunnyRoger1 year ago
Scary facts.
This is wrong in so many ways and quite disturbing as well come to think of it...
MAApleton1 year ago
I find this just a tiny bit silly, or it it just me?
jillef1 year ago
What about scanned documents? If a document if scanned from any scanner and then saved as a jpeg and sent as an email where the IP cannot be tracked is there any data that can be found then on those jpegs?
Thank you so much :) You made my day !!
heckstallw1 year ago
Its usful
rickafost1 year ago
sensational and informative
itsme1235 years ago
why could not you just print a blank page many times thru different printers ( or print in white something like a period). running it thru top first , then bottom first then thru other printers, it would be hard to tell which printer made which mark making it hard to tell exactly where each mark came from
vov35 itsme1233 years ago
It's impractical to do so on a regular basis to help prevent being spied upon, but yes, this would cause problems with their system. Congratulations, now the system is only useful for invading our privacy and not preventing fraud. :D
"It's outrageous that manufacturers make secret deals to compromise our privacy." What privacy? How many times do you send a letter to some one and you do not want them to know who sent it? This is not any different than your IP address being included in an email or saved at a website.
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