Message
Scanning opens the phone's mail app with the fields filled in. Nothing is sent until the person presses send, and a long body makes a dense code.
Preview
Enter an email address and the QR code will appear here.
Held in the hand. Keep the content short, because a long URL makes this too dense.
Rendered at 300 dpi for the physical size, at 85 × 55 mm. The destination is printed in small type beneath the code so a failed scan is not a dead end.
Kept in this browser so you can reopen and edit it later. Nothing is uploaded.
Design
The blank margin scanners use to find the code's edges. Four is the specified minimum, so the slider does not go lower.