Scan QR Codes Online from Your Camera or Image Files

Desktop users frequently encounter QR codes embedded in slide decks, invoices, software authentication screens, and marketing assets. Without an online scanner,

Similarly, QA engineers, graphic designers, and packaging specialists require a fast verification step during layout production. Before sending thousands of bro

All operations execute locally in your browser memory; confidential files never leave your device.

Access and process files directly on Android, iOS, Windows, and macOS without installing extra software.

The image is converted to grayscale, and an adaptive thresholding algorithm separates dark foreground modules from light background modules, compensating for uneven shadows or paper glare.

The algorithm searches for the three prominent 7×7 module concentric squares located at the top-left, top-right, and bottom-left corners. These patterns exhibit an invariable 1:1:3:1:1 width ratio of dark-to-light transitions along any scan line, allowing the scanner to determine the code's orientation and scale regardless of rotation.

Using the finder patterns and secondary alignment patterns (found in Version 2 and larger codes), the software establishes a coordinate grid, mathematically unwarping perspective distortion caused by camera tilt.

QR codes utilize Reed-Solomon algebraic error correction across four standard levels: Low (L, 7% recovery), Medium (M, 15% recovery), Quartile (Q, 25% recovery), or High (H, 30% recovery). The decoder evaluates the polynomial parity words to detect and reconstruct missing or corrupted modules caused by scratches, tears, or obscured areas.

The grid is multiplied against one of eight standard grid masks to reveal the underlying binary stream, which is decoded into numeric, alphanumeric, 8-bit byte, or Kanji data based on the mode indicator header.