- Does the QR code expire?
- No. The code holds your text itself, so it works for as long as that text (for example the link) does. It is not a redirect through a third party service.
- Which error correction level should I pick?
- Medium is a good default. Higher levels let a code survive scratches or a logo on top, but they add modules, so the code gets denser and harder to scan at small sizes.
- What is the quiet zone?
- The empty border around the code. Scanners use it to find the edges, and the QR standard asks for 4 modules. Cropping it too tightly is the most common reason a code fails to scan.
- PNG or SVG?
- SVG stays sharp at any size, so use it for print and posters. PNG is fine for screens and documents.