# QR Code Generator (print-ready)

> QR codes for links, text, Wi-Fi, contacts and more — as vector PDF, SVG and PNG. Encode a link, text, Wi-Fi login, contact card, e-mail, phone, SMS or map location as a QR code following ISO/IEC 18004 (versions 1–40, error correction L/M/Q/H, optimal mode switching, all eight masks scored). Get a print page with a test square, the code alone as SVG and PNG, a sheet of copies or Wi-Fi guest cards.

Part of usefulweb.app (https://usefulweb.app/). Part of [Printshop](https://printshop.usefulweb.app/) (ownerApp: printshop). Results are deterministic calculations from the inputs and the listed assumptions; the API returns exactly what the web page shows.

## Use it
- Human interface: https://printshopqrcode.usefulweb.app/ (interactive tool at https://printshopqrcode.usefulweb.app/tool)
- JSON API: POST https://printshopqrcode.usefulweb.app/api/v1/calculate with a JSON object of inputs (schema: https://printshopqrcode.usefulweb.app/api/v1/tool)
- OpenAPI: https://printshopqrcode.usefulweb.app/openapi.json
- MCP (Streamable HTTP): https://printshopqrcode.usefulweb.app/mcp - tool `printshop_qr_code`

## Inputs
- content (select): Content type
- text (textarea): Content - The address, text, e-mail address, phone number or "latitude, longitude". Not used for Wi-Fi.
- ssid (text): Wi-Fi network name (SSID)
- password (text): Wi-Fi password - Only used for the code; it is not shown in the result or stored in the share link.
- security (select): Wi-Fi security
- hidden (boolean): Hidden network
- layout (select): Print layout
- ecc (select): Error correction
- size (number): Code width (mm, with quiet zone)
- quiet (integer): Quiet zone (modules)
- dark (text): Dark colour
- light (text): Light colour
- logo (number): Logo-safe area (% of the code width) - Leaves an empty square in the centre for a logo and checks it against the error correction.
- caption (text): Caption under the code
- paper (select): Paper size
- orientation (select): Orientation

## Method
- Data is split into numeric, alphanumeric and byte (UTF-8) segments with the fewest bits (dynamic programming over the bit costs of ISO/IEC 18004 §7.4); the smallest version 1–40 that holds it at the chosen error-correction level is used.
- Reed–Solomon error correction over GF(256) (polynomial 0x11D), block interleaving after Table 9, all eight masks scored with the four penalty rules and the lowest chosen; format and version information use the BCH codes of §7.9–7.10.
- The logo-safe area clears the centre modules (never finder, timing or alignment patterns) and counts, per Reed–Solomon block, how many codewords it touches; the area is reported safe only when that stays within half of the block’s error-correction codewords.
- Wi-Fi codes use the WIFI:T:…;S:…;P:…;; format read by phone cameras (special characters escaped). Pages print at true size with a 20 mm (or 1 in) test square.

## Limits
- “QR Code” is a registered trademark of DENSO WAVE INCORPORATED. Test a printed code with the phones of your audience before printing many copies.