QR Code & Barcode Blog

How QR code check-in works end to end: what the code should contain, how fast a lane really is, how many lanes you need, and where duplicate detection breaks.

A QR code version is a grid size, not a release number - 21x21 up to 177x177. The full table, which version your data lands in, and what it costs in print.

Scammers stick their own QR codes over the real ones on parking machines. How to check a parking code in fifteen seconds, and what to do if you already paid.

Badge codes come in two kinds: one carries your contact details in plain text, the other a meaningless ID. How to tell which you are wearing in ten seconds.

Yes — a screenshot is a perfect copy. Whether it still works at the gate depends on one thing: whether your ticket's code refreshes. How to tell which you have.

Barcode width is arithmetic, not a guess. How the X-dimension, symbology and quiet zones decide the printed size, with the formulas and worked examples.

Apple Wallet passes display eight barcode symbologies, four new in iOS 27. The exact list from Apple developer docs, and what to do if your card is not on it.

Some shop scanners physically cannot read a display. Why a laser scanner fails on a screen, which codes survive it, and the fixes to try at the counter in order.

The barcode on your door jamb is your 17-character VIN. Decode it here: manufacturer, model year, plant, serial, and the check digit that catches misreads.

The sticker trick beats both checks shop staff recommend. Here's the one test that sees what the till sees — do it at the counter, before you pay.

Every carrier tracking number carries a check digit you can verify offline. Here is the arithmetic by hand — and why a number that passes still proves nothing.

Yes — but not the way most people think. The printed pattern never changes. What changes is the redirect behind it, and that matters on both sides of the scan.

The square on a rail e-ticket is an Aztec code, not a QR code. Here is the envelope it uses, the fields inside it, and why it can carry your ID document number.

Your iPhone camera reads QR codes and nothing else. The framework underneath it reads nineteen symbologies. Which formats work, on which phone, and why.

Accents, curly quotes and the euro sign break QR codes for two different reasons. One destroys your data at generation; the other is only a misreading.