QR code Wi-Fi password generator: the WIFI: format explained
A Wi-Fi QR code is a 60 character text string wrapped in pixels. Knowing the format is the difference between a sticker that joins guests in one tap and a sticker that prints fine, scans fine, and silently does nothing.
The WIFI: format, field by field
The format is informally specified by Android and now respected by iOS, Windows and most Linux phones. The full string lives on a single line and looks like this:
WIFI:T:WPA;S:CafeGuest;P:tortilla2026;H:false;;Four fields matter:
- T: is the security type. Valid values are WPA (covers WPA, WPA2 and WPA3 in practice), WEP (still scanned, do not use it for new networks) and nopass for open networks. If you put WPA2 here, some Android builds reject the payload silently.
- S: is the SSID. If your SSID contains a literal ;, ,, : or backslash, escape each one with a backslash. The SSID is case sensitive.
- P: is the password. Same escaping rules as the SSID. Omit the field for nopass networks.
- H: is whether the network is hidden. true if the SSID is not broadcast, false or omitted otherwise. Hidden networks fail to join silently if you forget this flag.
The string ends with a double semicolon. The terminator is part of the spec and a few parsers will fail without it.
What the phone actually does
When the camera app reads the code, the OS recognises the WIFI: prefix and offers a "Join network" prompt instead of opening a browser. The user taps once and the device writes the credentials into its saved networks list. No keyboard, no typos.
iOS adopted the format in iOS 11 (2017), Android has supported it since 10 (2019), and the default camera apps on Pixel and Samsung trigger the prompt without any third party scanner. On older Android the user needs Google Lens or a QR app, the encoding is identical.
Security: who you give the QR to
A Wi-Fi QR is a credential printed in plain text. Anyone with a phone camera and 1.5 seconds of line of sight reads it. Treat the sticker like the password itself.
For a coffee shop guest network this is fine, the password is meant to be public. For a corporate office or your home network, do not laminate the QR onto a public board, do not post it on Instagram, and consider an isolated guest VLAN with rate limiting if you do display a code at all. The QR is a convenience for trusted scanners, not an authentication mechanism.
Common reasons a code does not join
Three failure modes cover most support tickets. Wrong security type: T:WPA2 instead of T:WPA, the parser bails. Unescaped special characters in the password: a ; in your password splits the field early, the phone joins with a truncated password and rejects. Hidden network without H:true: the phone does not probe for the SSID and the join times out. Test the QR on both an iPhone and a recent Android before you print 200 stickers.
Working example
text# Working WIFI: payload, ready to encode as a QR
WIFI:T:WPA;S:CafeGuest;P:tortilla2026;H:false;;
# Open guest network, no password
WIFI:T:nopass;S:LobbyOpen;;
# Hidden corporate SSID, password contains a semicolon
WIFI:T:WPA;S:OfficeIoT;P:line1\;line2;H:true;;Just need the result?
Type the SSID and password into the QR code generator on aldeacode.com and the tool builds the WIFI: string and renders a clean code in your browser, no upload, no account. Print it on the menu, on the guest room mirror, on a sticker by the desk.
Open QR Code Generator →Frequently asked questions
Does the WIFI: format support WPA3?
Yes, use T:WPA. The format does not distinguish WPA, WPA2 and WPA3, the phone negotiates the strongest protocol your router supports. Do not write T:WPA3, several Android parsers reject it.
My SSID has spaces and an apostrophe, do I escape them?
Spaces are fine, no escaping needed. Apostrophes are fine. Only backslash, semicolon, comma and colon must be prefixed with a backslash. UTF-8 SSIDs work, the phone reads them correctly.
Can I add a Wi-Fi QR to a printed business card?
Technically yes, in practice it leaks your home credential to anyone who keeps the card. Use a guest network with a rotating password, or skip the Wi-Fi QR and put a vCard QR instead.