Short answer
A Wi-Fi QR code holds a short text in the WIFI: format with the network name, security type and password. Current iPhone and Android cameras recognise it and offer to join the network. This generator builds that text in your browser, so the password never leaves your device.
What the code actually contains
A Wi-Fi QR code is not a link and does not go through any website. It holds a few lines of text in a format first documented by the open-source ZXing barcode project and now read by phone cameras:
WIFI:T:WPA;S:Cafe Guest;P:espresso-2026;;
T is the security type (WPA, WEP or nopass for an open network), S is the network name, P is the password, and an optional H:true marks a hidden network. The double semicolon ends the record. Because ;, :, ,, " and \ are part of the syntax, any of those characters inside your name or password must be preceded by a backslash. The generator does that automatically, which is where hand-typed codes usually go wrong.
Getting it right the first time
- Copy the name from the router or its admin page. Network names are case-sensitive. "CafeGuest" and "cafeguest" are two different networks to a phone.
- Check for trailing spaces. A space at the end of the password is a real character. If you copied it from somewhere, look at the payload box to be sure.
- Use a guest network. Most routers can run a separate guest network that can reach the internet but not your printers, cameras or file shares. Print that one.
- Test on two phones. One iPhone and one Android if you can, standing where your guests will stand.
Where to put it
Table tents, the back of a menu, a framed card by the door, a welcome sheet in a rental, a sticker on a meeting room screen. For a table tent read from a chair, 4 to 5 cm across is plenty. For a sign across a room, use the size calculator. Add a short line of text next to the code, such as "Scan to join the guest Wi-Fi", and print the network name and password too for people whose phones won't scan.
When the password changes, make a new code and replace every printed copy. A print template makes that a two-minute job.
Sources
Questions
Is it safe to put my Wi-Fi password in a QR code?
The code contains the password in plain text, so anyone who scans it can read it, exactly as if it were written on a card. Use it for a guest network, not the network your office files sit on. If the password changes, the code stops working and you need a new one.
Which phones can scan it?
The built-in camera app on current iPhones and most Android phones reads Wi-Fi codes and shows a Join prompt. Older Android phones may need Google Lens or the camera's QR mode.
My network name has a semicolon or colon in it. Will it work?
Yes. Backslash, semicolon, comma, colon and double quote have special meaning in the WIFI: format, so the generator escapes them with a backslash for you. You can see the exact text under 'What's inside the code'.
What about WPA3?
Choose WPA / WPA2 / WPA3. Phones negotiate the actual protocol with the router; the code only needs to say that a password is required.
Does the code work for hidden networks?
Tick 'Hidden network'. That adds H:true, which tells the phone to look for the network even though it isn't broadcasting its name.