A Wi-Fi code your guests can just point a camera at

Type the network name and password, and the code below becomes one a phone can join from. iOS has read these natively since iOS 11 and Android since 10, so there is nothing for a guest to install and nothing for them to type — which is the entire point, because a café password is usually a long string chosen to be hard to guess and it is therefore hard to type.

The password is inside the image, and you cannot take it back

This is the fact worth knowing before you print one. A Wi-Fi code is static by nature: the network name and the password are encoded into the pattern itself, so anyone who photographs the card on your counter has your password for as long as it stays unchanged. There is no revoking it and no expiry — not because we have not built that, but because there is nothing in the middle to switch off. If that matters, put guests on a separate guest network and print a code for that one, which is what the code is genuinely good at.

Get the security setting right or nothing happens

WPA/WPA2 covers essentially every home and office router made this century, and it is the default here. Pick "Open" only for a network with no password at all — choosing it for a protected network produces a code that scans perfectly, says it joined, and then fails, which is far more confusing than a code that does not scan. WEP is only for equipment old enough that it should be replaced rather than labelled.

Print it big enough for the room it is in

A tent card on a table is read from about 40cm and can be small. A code stuck on a window for the street is read from three metres and needs to be roughly ten times bigger than people expect. The rule of thumb is that the printed code should be about a tenth of the distance it is scanned from. Download the SVG or PDF for anything going to a printer, because a PNG enlarged to poster size gives you soft edges and a code that phones hesitate over in poor light.

What goes in it

• Network name (required)
• Security
• Password
• Hidden network

Questions

Does a Wi-Fi QR code work on iPhone and Android?

Yes, both, straight from the camera app — iOS since iOS 11, Android since 10. Older Androids may need a QR scanner app. There is nothing to install on the guest side of a modern phone.

Can I change the password later without reprinting?

Not with a Wi-Fi code, because the password is in the pattern itself. If you expect to rotate it, print a dynamic code that points at a small page showing the current password instead: then the printed card stays valid and you edit the page.

Does the code work if my network is hidden?

Yes — tick "Hidden network" and the code tells the phone to look for a network that does not broadcast its name. Leaving it unticked for a hidden network is the usual reason a correct-looking code silently does nothing.