PDF417 and Aztec Codes: The Barcodes on Your Boarding Pass
What's the barcode on your boarding pass? Often it isn't a QR code at all. It's PDF417 or Aztec.
PDF417 is a stacked barcode: rows of codewords, each made of 4 bars and 4 spaces across 17 modules. You'll find it on driver's licences, ID cards and printed boarding passes. Aztec grows out from a bullseye in the centre and needs no quiet zone, which makes it popular on phone tickets and rail tickets. Airlines share one IATA standard for bar-coded boarding passes, and the code is readable plain text: your name, booking reference and flight, which is why you shouldn't post it online. Event tickets usually hold just an ID that the gate checks once, sometimes rotating. We finish with MaxiCode (on UPS parcels), Han Xin and DotCode, and whether your phone can read them.
A boarding pass, a driver's license, a concert ticket on your phone.
Each one carries a code, and often it isn't a QR code.
So what are these codes, and what do they hold?
Start with the long, striped one.
It's called PDF417.
It's a stacked barcode.
Three to 90 rows, each one read like a small barcode of its own.
The name tells you how it's built.
Every code word has four bars and four spaces across 17 modules.
It's on printed boarding passes and on most driver's licenses and ID cards in the US and Canada.
On a phone you'll often see this one instead, an Aztec code.
Its finder is a bullseye in the center.
Scanners read it from the middle out so it needs no quiet zone.
That makes it a good fit for tickets and it's common on rail tickets in Europe.
Airlines share one standard for this, from IATA, so any airport can read any airline's pass.
Printed passes use PDF417.
Mobile passes can use Aztec, QR, or Data Matrix.
Inside is plain text.
Your name, booking reference, airports, flight, the day of the year, and your seat.
That's why you shouldn't post a photo of your boarding pass.
Your name and booking reference can be enough to open your booking.
Event tickets are simpler.
The code usually holds just a ticket number.
At the door, the scanner looks it up and marks it as used, so a copy can't get in twice.
And some ticket apps show a code that changes every few seconds, so a screenshot stops working.
A few more cousins.
MaxiCode, built from hexagons, sorts parcels at UPS.
Han Xin was made in China for Chinese characters.
And DotCode prints as separate dots on fast production lines.
So can your phone read them?
Many scanner apps can.
The built-in camera mostly looks for QR codes.
Those codes are for gates and scanners.
Yours can be for people.
AriaQR turns any image into a QR code that still looks like your image.
Tested on real scanners before you pay.
Make yours at ariaqr.com.
Those codes are for gates and scanners. Yours can be for people.
