Last updated: October 2026 Β· 3 min read
From paying the chaiwala by UPI to opening a restaurant menu, QR codes are everywhere in India. A QR (Quick Response) code is a two-dimensional barcode that a phone camera can read in a fraction of a second.
A short history
QR codes were invented in 1994 by Masahiro Hara at Denso Wave, a Japanese company, to track car parts. They are free to use, which helped them spread worldwide.
What is inside a QR code
- Three finder patterns (big squares in corners) tell the camera where the code is and how it is rotated.
- Alignment and timing patterns help read codes that are bent or tilted.
- Data modules: the small black and white squares that store information as binary 1s and 0s.
- Error correction: extra data that lets the code work even if part of it is dirty or torn, up to about 30% at the highest level.
How your phone reads it
- The camera spots the three finder squares.
- Software straightens the image.
- It reads the pattern of modules as bits.
- Error correction fixes damaged bits.
- The decoded text, such as a UPI payment link, is shown or opened.
Why UPI uses QR codes
A UPI QR code contains a payment link with the merchant’s UPI ID and name, and sometimes a fixed amount. Shops need only a printed sticker, which made digital payments cheap enough for street vendors. Interoperable standards such as Bharat QR and UPI QR let one code work with all UPI apps.
Static vs dynamic QR
| Static QR | Dynamic QR | |
|---|---|---|
| Content | Fixed (UPI ID) | Changes per transaction (amount, order ID) |
| Used by | Small shops | Billing counters, online checkout |
| Amount | Customer types it | Pre-filled |
How to avoid QR code scams
- You never need to scan a QR code or enter your PIN to receive money.
- Check the payee name shown in your UPI app before paying.
- Watch for stickers pasted over a shop’s real QR code.
- Avoid scanning QR codes from unknown messages or posters offering prizes.
Frequently asked questions
How much data can a QR code hold?
Up to about 4,296 letters and numbers or 7,089 digits in the largest version, though most codes hold far less.
Do QR codes expire?
Static codes do not. Dynamic codes can be set to expire by the system that created them.
Can I make my own QR code?
Yes, many free generators exist. For UPI, download your official QR from your bank or UPI app.
Keep exploring
Facts are based on widely accepted official, scientific and historical sources at the time of writing. Spotted something that needs updating? Let us know.
