QR Code Generator

ISO/IEC 18004:2024 (Edition 4, August 2024) defines four error-correction levels (L, M, Q, H) using Reed-Solomon codes (Reed & Solomon, 1960, J. Soc. Ind. Appl. Math. 8(2):300–304). Level L recovers up to ~7% of the codeword bytes; M up to ~15%; Q up to ~25%; H up to ~30%. The codeword bytes encode the user data plus Reed-Solomon parity; the more parity, the more dirt, damage, or logo overlay a scanner can compensate for, but the more module space the QR uses for the same payload (a level-H QR for the same URL is denser and physically larger than the level-L version). This page defaults to M because it is the universal compromise: enough resilience for printed business cards or stickers without dramatically inflating QR size for typical URL or text payloads.

ISO/IEC 18004:2024 specifies QR versions 1 to 40, where the version number determines the symbol's module count (21×21 modules for version 1, 177×177 for version 40). Capacity scales with both version and error-correction level: at version 40 / level L, a QR holds up to 7,089 numeric digits, 4,296 alphanumeric characters, 2,953 binary bytes, or 1,817 Kanji characters. Most everyday use (a URL, a Wi-Fi share code, a vCard) fits well within version 1–15. Above that the modules become too small to scan reliably from a phone camera at typical distances. For very long payloads, the better pattern is encoding a short URL that resolves to the long content rather than fitting the full payload into a giant QR.

The Wi-Fi share code format originated in the ZXing open-source library (github.com/zxing/zxing/wiki/Barcode-Contents) and became the de facto cross-platform standard — Android Camera supports it since Android 10, iOS Camera since iOS 11. The string format is `WIFI:T:authType;S:SSID;P:password;;`, where authType is WPA / WPA2 / WPA3 / WEP / nopass and the trailing `;;` signals end-of-record. Special characters `;`, `,`, `:`, `\`, and `"` inside SSID or password must be escaped with a backslash; for example, an SSID literally 'Cafe;Bar' encodes as `S:Cafe\;Bar`. The optional `H:true` field marks an SSID as hidden. The order of fields does not matter to the spec, but the trailing `;;` is structural — without it, parsers may treat the next field as a continuation of the previous record.

QR Code is the symbology — the visual encoding from ISO/IEC 18004:2024. vCard, Wi-Fi share, and payment formats (EMVCo for global merchant-presented QR, adopted nationally in Singapore, India, South Africa, Colombia and others; EPC for SEPA credit transfers in Europe) are payload conventions. A QR Code with a vCard payload is just a QR Code whose decoded text starts with `BEGIN:VCARD` and follows RFC 2426 (v3.0, 1998) or RFC 6350 (v4.0, 2011) syntax. Modern phones recognize the payload prefix and offer a contextual action — 'Add to Contacts' for vCard, 'Connect to Wi-Fi' for the ZXing format, 'Open in browser' for plain URLs. This page generates a v3.0 vCard because every modern phone parses it; v4.0 has slightly newer features (RELATED property, expanded URL semantics) but is not universally supported on older OS versions.

The QR canvas carries an alt-text label describing the encoded payload, the live preview region is marked aria-live="polite" (W3C WCAG Success Criterion 4.1.3 Status Messages, introduced in WCAG 2.1, Recommendation 5 June 2018; carried unchanged into WCAG 2.2, Recommendation 5 October 2023), and the foreground/background color picker enforces a minimum contrast ratio so the resulting QR remains scannable by camera apps that depend on contrast — a yellow-on-cream QR may meet WCAG visual contrast thresholds for humans but still fall below the contrast headroom most camera decoders need. Screen readers (NVDA, JAWS, VoiceOver) consume the live region automatically when the encoded value updates.