QR Code Generator

How QR Codes Work

A QR (Quick Response) code is a two-dimensional matrix barcode invented in 1994 by Denso Wave, a subsidiary of Toyota, for tracking automotive parts. Unlike traditional one-dimensional barcodes that store data in horizontal lines, QR codes use a grid of black and white modules (squares) to encode data in two dimensions — both horizontally and vertically.

Every QR code contains several structural elements: finder patterns (the three large squares in the corners) help scanners detect and orient the code; alignment patterns help correct for distortion; timing patterns establish the grid size; and format/version information tells the scanner which encoding and error correction level is used. The remaining modules store the actual data.

Error correction is built into every QR code using Reed-Solomon codes. This means a QR code can still be read even if up to 30% of it is damaged, covered, or obscured — which is why QR codes with logo overlays still scan correctly (as long as the overlay doesn't cover too much of the data area).

Common Uses for QR Codes

URLs and websites: The most common use. Scanning the code opens a web page instantly — perfect for marketing materials, product packaging, and business cards.
Wi-Fi access: QR codes can encode your network name, password, and security type. Guests scan to connect without typing long passwords.
Contact information: vCard QR codes let people save your contact details directly to their phone by scanning.
Payment: Services like PayPal, Venmo, and WeChat Pay use QR codes for quick mobile payments.
Authentication: Two-factor authentication apps (Google Authenticator, Authy) use QR codes to set up new accounts.
Ticketing: Airlines, trains, events, and movie theaters use QR codes as digital tickets that can be scanned at the gate.

Frequently Asked Questions

What is a QR code?

A two-dimensional barcode that stores data in a matrix of black and white squares. Invented in 1994, QR codes can encode URLs, text, Wi-Fi credentials, contact info, and more. Any smartphone camera can scan them.

How do I scan a QR code?

Open your smartphone camera and point it at the QR code. A link or notification will appear — tap to open. Both iOS (11+) and Android (9+) support native scanning. Older devices may need a QR scanner app.

What is error correction in QR codes?

Error correction lets a QR code be read even when partially damaged. Level L recovers 7%, M recovers 15%, Q recovers 25%, and H recovers 30%. Use H if adding a logo overlay.

How much data can a QR code hold?

Up to 7,089 numeric characters, 4,296 alphanumeric, or 2,953 bytes. For reliable scanning, keep data under 300 characters.

What is the best QR code format for printing?

SVG for print (vector, scales infinitely without quality loss). PNG for digital use. Always use SVG for large-format printing like posters and banners.