How to make a QR code
Making a QR code takes about thirty seconds. Making one that still works on a wet menu, a curved bottle or a poster read from four metres away takes a little more thought. This is the part most generators skip.
Start with what happens after the scan
The code is the easy half. Before you generate anything, open your destination on a phone and time how long it takes to become useful. A slow page or a PDF that needs pinching kills more scans than a badly printed code ever will.
Choose static or dynamic
Static means the destination lives inside the pattern: permanent, free to run, impossible to change. Dynamic means the pattern holds a short forwarding address you control. If the code is going anywhere you cannot easily reprint, choose dynamic.
Keep the contrast high
Dark dots on a light background is what scanners expect. Inverted codes work on some phones and fail on others. If you must tint the background, keep it pale, and never place the code over a busy photograph.
Size it for the distance
The working rule is one centimetre of code per ten centimetres of expected scanning distance. A table card read from forty centimetres wants four centimetres of code. A poster read from three metres wants thirty.
Leave the quiet zone alone
The blank margin around a code is part of the code. Four modules of clear space on every side is the standard, and crowding it with text is the single most common reason a printed code fails.
Test on real phones
Test with at least one iPhone and one Android device, in the light the code will actually live in. A code that scans on a bright monitor can fail on a dim restaurant table.
The generator is free and needs no account to preview.
Questions
How long does a QR code last?
A static code lasts forever because nothing has to stay online for the pattern to decode. A dynamic code lasts as long as the forwarding service runs.
Can QR codes carry viruses?
The code itself is only text. The risk is where it sends you, which is why scanning stickers placed over legitimate codes in public is genuinely dangerous. Check the address your phone previews before tapping.