Free QR code reader tool guide. Learn how QR codes store data, how scanning works, and how to decode QR codes from images online without a phone.
QR codes are two-dimensional barcodes that can store up to 3KB of data. They're used everywhere - menu links, WiFi passwords, product information, payment systems. But sometimes you have a QR code image on your computer and need to decode it without a phone.
Our QR Code Reader decodes QR codes from uploaded images.
How QR Codes Store Data
A QR code uses a grid of black and white squares. Three corner squares help the scanner detect orientation. The rest encodes the data using Reed-Solomon error correction, which means even if part of the code is damaged or obscured, it can still be read. There are four error correction levels - higher levels can handle up to 30% damage but store less data.
What You Can Store
- Text - Up to 4,296 alphanumeric characters
- URLs - Most common use, up to about 2,000 characters
- Contact info - vCard format for adding to address books
- WiFi credentials - Network name and password for easy connection
- Email or SMS - Pre-filled message templates
Upload a screenshot or photo of any QR code and the reader decodes it instantly.