QR Code Generator

How QR codes work — and why error correction matters

A QR code stores your text as a grid of black and white modules with Reed–Solomon error correction woven through it. That redundancy is why a scuffed, partially covered or logo-stamped code still scans. The four levels trade capacity for resilience: L survives ~7% damage, M ~15%, Q ~25% and H ~30%. Higher levels produce denser codes for the same content, so there's a real trade-off — use L or M for screen-displayed codes that will never be damaged, and Q or H for anything printed, laminated, stuck outdoors, or overlaid with a logo. Shorter content always helps: a link shortened before encoding yields a coarser, easier-to-scan grid than a 200-character URL.

Wi-Fi QR codes: how the format works

The Wi-Fi tab builds a payload in the de-facto standard format WIFI:T:WPA;S:MyNetwork;P:secret;; — security type, SSID and password, with special characters backslash-escaped. Both iOS (11+) and Android recognise it natively in the camera app: point, tap, and the phone joins the network without anyone typing a 20-character passphrase. It's the standard trick for guest Wi-Fi in offices, cafés and rental apartments — print the code, frame it, done. Note the password is stored in the code in plain text (that's what lets the phone join), so only share the printout as widely as you'd share the password itself.

FAQ

Do these QR codes expire or have a scan limit?

Never. This generator produces static QR codes: your text is encoded directly into the image itself, with no redirect service in between. It works forever, offline, with no tracking — unlike "dynamic" QR services that route scans through their servers and can expire, paywall or analytics-gate your code.

What size should I download for print?

Aim for at least 300 px for a business-card-sized code and 1024 px for a poster. The PNG here is generated at exactly the size you pick with crisp module edges. Two rules of thumb for the physical world: keep the printed code at least 2 × 2 cm, and expect a scan distance of about 10× the code's width.

Is it safe to generate a QR code for my Wi-Fi password?

The code is rendered entirely in your browser by the open-source qrcode library — your SSID and password are never sent to any server, and nothing is stored when you leave the page. The only copy that exists is the PNG you download.