Free QR code generators: link, WiFi, vCard, SEPA payment

A QR code is a string encoded as squares, and the phone decides what to do with it by recognising the shape of that string. Getting the shape right by hand means knowing four or five small formats and their escaping rules, and one wrong character produces a code that scans perfectly and does nothing. Each generator here writes its own format, tells you whether the print will scan, and stores nothing: the codes are static, with no service between them and their destination, so they work in ten years.

Which generator answers which question

• A QR code for a link, a phone number, a place or an event? The QR code generator writes the right string for each, gives PNG and SVG, measures the contrast of your colours, prints a sheet, and reads a code back from a picture.
• Let guests join the WiFi without spelling the key? The WiFi QR code generator encodes the network, escapes the punctuation that breaks hand-written codes, and prints a guest card. The key is never stored.
• Hand over a contact that imports correctly? The vCard QR code generator carries a vCard 3.0 that phones read, shows what the address book will receive, and makes an e-mail signature and a sheet of business cards.
• Put a scan-to-pay code on an invoice? The SEPA payment QR code generator follows the EPC069-12 standard, so the payer's banking app opens a transfer already filled in, after the IBAN has been checked.

What makes a printed code scan

Three things, none visible on a screen at 300 pixels: the quiet zone around the symbol, the size of each square once printed, and the contrast between the two colours. Every generator here reports them before you print, and gives an SVG so the size stops mattering. None of them add a logo in the middle, because a code whose only job is to scan should simply scan.