What is QR code?

A QR code is a square barcode that stores a short piece of text, most often a web address, which a phone camera can read in a moment. QR codes were invented in 1994 by Denso Wave for tracking car parts. Today the built-in camera apps on iPhone and Android can read them without an extra app.

They are handy for moving a download link from a computer to a phone: show the code on screen and scan it, with no typing.

Only scan codes from sources you trust, and check the address your phone shows before opening it.

1. Upload your files as a link transfer.
2. When it finishes, a QR code appears next to the link. The other person points their phone camera at it and the download page opens.
3. Use Share QR or Download QR to send the code as an image.
4. For a wall, desk or slide, open your Transfers page and choose More > QR poster, add a title and print it or save it as a PDF.

• Size: print it large enough to scan from where people will stand. A few centimetres across is fine on a desk; a poster across a room needs a much bigger code.
• Contrast: dark code on a light background, with a clear margin around it.
• Short content: the more text a code holds, the denser it gets. A short link makes a simpler code that scans more easily.
• Context: add a line of text saying what it opens and when it expires.
• Test it with two different phones before printing many copies.

A QR code can hide any web address, and fake codes stuck over real ones are a known scam. Before you tap, read the address your phone shows. Be wary of codes that lead to login pages or ask for payment details, and do not install apps from a code you were not expecting.