QR Code Generator
Generate QR codes from URLs, text, or WiFi credentials. Customize size and error correction level.
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| Level | Recovery | Numeric | Alphanumeric | Binary |
|---|---|---|---|---|
| L | 7% | 7,089 | 4,296 | 2,953 |
| M | 15% | 5,596 | 3,391 | 2,331 |
| Q | 25% | 3,993 | 2,420 | 1,663 |
| H | 30% | 3,057 | 1,852 | 1,273 |
How QR Codes Work
QR codes (Quick Response codes) were invented in 1994 by Masahiro Hara at Denso Wave, a Toyota subsidiary, originally to track automotive parts in manufacturing. A QR code is a two-dimensional matrix barcode that encodes data in a grid of black and white squares. Unlike one-dimensional barcodes that encode data horizontally only, QR codes encode data in both dimensions, dramatically increasing data density.
Anatomy of a QR Code
A QR code is composed of several distinct functional regions. The three finder patterns — large black squares in three corners — let scanners quickly detect and orient the code. Timing patterns are alternating black and white rows that help the scanner determine the grid size. Alignment patterns appear in larger QR codes to correct for image distortion.
Reed-Solomon Error Correction
QR codes use Reed-Solomon error correction, the same algorithm used in CDs, DVDs, and deep-space communication. This means a QR code can still be scanned even if part of it is damaged, dirty, or covered. The four error correction levels — Low (7%), Medium (15%), Quartile (25%), and High (30%) — represent the percentage of codewords that can be restored if damaged.
QR Code Applications
QR codes have become ubiquitous in modern life. Contactless payments (Apple Pay, Google Pay, WeChat Pay) use QR codes extensively. Restaurant menus shifted to QR codes during COVID-19. WiFi sharing is simplified with WPA QR codes that encode credentials. Two-factor authentication (2FA) apps like Google Authenticator use QR codes to share TOTP secrets during setup.
QR Code Security Risks — QRishing
QR codes present unique security risks because humans cannot visually inspect the encoded URL before following it. This enables "QRishing" (QR phishing) attacks where malicious QR codes replace legitimate ones on parking meters, restaurant tables, or in emails. The FBI and FTC have both issued warnings about QRishing targeting banking and government services.
Creating Safe QR Codes for Your Organization
When generating QR codes for public use, always use HTTPS URLs to protect users in transit. Avoid URL shorteners in QR codes as they obscure the final destination. Add your organization's logo and use high error correction level (H) to accommodate the logo overlay without sacrificing scannability. Always test QR codes on multiple devices before printing or publishing.