QR Code Generator

The encoder follows ISO/IEC 18004 (QR Code model 2) and runs entirely on this page. The text is analysed for the densest mode that holds it — numeric (3⅓ bits per digit), alphanumeric (5½ bits per character; digits, capitals and nine symbols) or byte (8 bits per UTF-8 byte) — and the smallest version from 1 (21 × 21 modules) to 40 (177 × 177) whose data capacity fits at the chosen error-correction level is used. Reed–Solomon error-correction codewords are computed over GF(2⁸) for each block, interleaved with the data, placed in the standard zigzag, and one of eight masks is applied: the page scores all eight with the standard's four penalty rules and keeps the lowest. Format and version information carry their own BCH codes. Every module you see is the result of that arithmetic, which is why the page can state the version, mask and capacity rather than guess at them.

Level L allows about 7 % of the codewords to be damaged and still decode, M 15 %, Q 25 %, H 30 %. Higher levels cost capacity, so the same text needs a larger version: a 40-character URL is version 3 at L and version 5 at H. M is the usual choice for screens and clean print; H is worth it when the code carries a logo or lives outdoors. Data capacity is shown as bits used of bits available, so you can see how close the next version is. A URL written in upper case fits alphanumeric mode and can drop a version — the page says when that applies.

The standard requires a quiet zone of four light modules on every side; the SVG includes it and the page warns if you reduce it. Dark modules must be darker than the background — an inverted symbol decodes on few readers — and the colour warning uses the WCAG contrast ratio as a plain measure. Byte data is written as UTF-8 without an ECI header, which is what phone cameras assume. The SVG is drawn with one path and crisp edges so it scales to any print size; the PNG is rasterised in your browser at the pixel size you choose. Test the printed result with the reader your audience uses.

Symbols for sample texts across versions 1 to 8, all four levels and every mask were compared module for module with an independent encoder; the block-structure table (error-correction codewords per block and blocks per version) was compared entry by entry with the same encoder's table, and the format and version examples printed in the standard's annexes are asserted by the tests. That comparison caught two transposed table entries and a reversed generator polynomial during development — errors that would have produced symbols that look right and do not scan.

No dynamic codes: the URL you encode is the URL in the symbol, with no redirect through this site and therefore no scan counts, expiry or editing later — a code you download works forever and belongs to you. No logos, rounded modules or gradients: those reduce reliability and are better added in artwork on top of a level-H symbol. Kanji mode, Micro QR and structured append are not offered. Nothing you enter leaves the browser; the same four anonymous usage counts as the rest of the site apply.