QR Code Generator

What Is a QR Code?

A QR code (Quick Response code) is a two-dimensional barcode invented by Denso Wave, a subsidiary of Toyota, in 1994. Originally designed to track automotive parts during manufacturing, QR codes have become ubiquitous in consumer and enterprise applications. Unlike traditional one-dimensional barcodes that store data in horizontal lines, QR codes use a matrix of black and white squares that can encode information both horizontally and vertically, dramatically increasing data capacity. A standard QR code can store up to 4,296 alphanumeric characters or 7,089 numeric digits.

How QR Codes Work

QR codes use Reed-Solomon error correction, a mathematical algorithm that adds redundant data to the code so it can still be read even if portions are damaged or obscured. This is why you can place a logo in the center of a QR code and it still scans — the error correction data compensates for the missing modules. The four levels (L, M, Q, H) trade data capacity for durability: Level H can recover data even if 30% of the code is damaged, but requires a larger code for the same data. The three large squares in the corners are finder patterns that help scanners detect and orient the code regardless of rotation.

Common QR Code Use Cases

• Website URLs: The most common use — QR codes on business cards, posters, product packaging, and advertisements link directly to websites without typing.
• Wi-Fi network sharing: Encode network name, password, and encryption type so guests can connect by scanning.
• Payment systems: Mobile payment platforms like Apple Pay, Google Pay, WeChat Pay, and UPI use QR codes for contactless transactions.
• Event tickets: Airlines, cinemas, and event venues use QR codes as digital tickets that can be scanned at entry points.
• Contact information: vCards encoded in QR codes allow instant contact sharing — scan to add someone to your phone.

QR Code Security

While QR codes themselves are harmless data containers, they can be used maliciously. QR phishing (quishing) involves placing malicious QR codes over legitimate ones — for example, replacing a restaurant's menu QR code with one linking to a phishing site. Always verify the URL after scanning before entering credentials, and be cautious of QR codes in public places that could have been tampered with. Use your phone's built-in QR scanner rather than third-party apps, as modern iOS and Android cameras show a URL preview before opening.