This code never stops working
Many QR sites make a "dynamic" code: it points at their own short address, which then sends people on to yours.
When the trial ends, or the company closes, every printed code dies with it.
The code made here holds your link itself.
There is nothing in between to switch off.
Error correction, in plain words
A QR code carries spare information, so a phone can still read it when part of it is missing.
The standard has four levels, keeping about 7%, 15%, 25% or 30% spare.
Every code made here uses the highest, 30%, so there is nothing to choose.
It makes the code a little denser, and it is what lets it survive a sticker that gets wet, scratched or folded.
A picture in the middle
The picture covers real squares, and the code survives only because of that spare information.
Every code starts with the Tublish logo there, which you can swap for your own picture or remove, and the picture stays at about a quarter of the width.
A long link needs the middle for the small squares that help a camera line the code up, so there the picture is left out, and the page says so.
Before you print
- Keep dark squares on a light background. Many phone cameras cannot read a reversed code, and the page warns you about one.
- Leave the white border alone. The margin around the code is part of it.
- Print it at least 2 cm (about 0.8 inches) wide, and bigger for a poster read from across a room.
- Scan the downloaded file with two different phones before you print a thousand of them.