QR codes (Quick Response codes) have become part of everyday life. Restaurants use them for menus, shops for payments, and WiFi networks for quick connection. But what are QR codes really and how do they work?

What is a QR code?

A QR code is a two-dimensional barcode that can contain up to 4,296 alphanumeric characters or 7,089 numeric characters. Unlike a regular barcode that has only horizontal lines, a QR code also has vertical lines, which allows it to store much more data.

The QR code was invented in 1994 in Japan, at Denso Wave company, for the automotive industry. Today it is used everywhere.

How does a QR code work?

A QR code consists of:

🔲 Position markers (3 large squares in corners) — help the scanner find and orient the code
⬛ Modules — black and white squares that encode data
🔧 Error correction codes — allow reading even if part of the code is damaged

Interesting: QR codes have 4 levels of error correction (L, M, Q, H). The highest level (H) can read the code even if 30% of the code is destroyed.

What can be in a QR code?

A QR code can contain:

🌐 URL — most common, leads to a website
📝 Text — any text up to 4,296 characters
📧 Email — address and message subject
📞 Phone number — call or SMS
📶 WiFi data — SSID and password
📍 Location — GPS coordinates
👤 vCard — contact data
💳 Crypto address — for payment

How to create a QR code?

Method 1: Online generator

The easiest way. Use our free ScanWeb QR Generator:

Choose content type (URL, text, email, WiFi)
Enter the content
Choose size
Download as PNG

Advantage: everything happens in your browser, the code is not sent to a server.

Method 2: Programmatically (for developers)

JavaScript library qrcode:

import QRCode from 'qrcode';
QRCode.toCanvas(canvas, 'https://scanweb.net', function(err) {
    if (err) console.error(err);
});

Method 3: Python

import qrcode
img = qrcode.make('https://scanweb.net')
img.save('qr.png')

How to scan a QR code?

Most modern phones have a built-in scanner in the camera. Just open the camera and point it at the code.

If your phone does not support QR scanning, install an app:

📱 Google Lens
📱 QR Code Reader
📱 Kaspersky QR Scanner (security-oriented)

Security warnings

QR codes can also be dangerous if you don't pay attention:

1. Fake QR codes

Attackers can stick their QR code over the real one (e.g. in a parking lot or restaurant). The scanner opens a fake site that looks real.

2. Malicious URL

A QR code can lead to a phishing page that asks for your data.

3. Automatic download

Some QR codes can trigger a file download or app installation.

How to protect yourself?

✅ Check the URL before clicking — do you see the domain before opening the link?
✅ Use apps with preview — some apps show content before action
✅ Don't scan unknown codes — especially in public places
✅ Watch for stickers — if it looks like a QR code is over another one, be suspicious

Creative uses of QR codes

🍽️ Restaurants — digital menu
🎁 Gifts — link to personalized message
📚 Books — link to additional content
🎵 Music — Spotify playlist
💼 Business cards — vCard contact
🏠 Real estate — virtual tour
🚌 Transport — schedule and tickets

Create your QR code

Try our free tool: ScanWeb QR Code Generator. Create QR codes for URL, text, email or WiFi network — all without upload.

Check out other ScanWeb tools.

QR Codes for Beginners — Everything You Need to Know