How do I create a QR code for WiFi sharing?

Use the WiFi format: WIFI:T:WPA;S:NetworkName;P:Password123;H:false;; where T is security type (WPA, WEP, nopass), S is the SSID, P is the password, and H indicates if it's a hidden network. Scanning automatically connects the device.

QR Codes Explained: Complete Guide for Developers and Marketers

Everything you need to know about QR codes: how they work, what data types they support, design best practices, and common use cases for business and development.

What Are QR Codes?

QR codes (Quick Response codes) are two-dimensional barcodes that store information in a pattern of black and white squares. Invented in 1994 by Denso Wave for tracking automotive parts, they've become ubiquitous for sharing URLs, contact information, WiFi credentials, and more.

QR Code vs Traditional Barcode

Feature	Traditional Barcode	QR Code
Dimensions	1D (horizontal lines)	2D (matrix)
Data Capacity	~20 characters	~4,296 characters
Data Types	Numbers only	Text, URLs, binary
Error Correction	None	Up to 30% recovery
Scan Angle	Must be horizontal	Any orientation

Anatomy of a QR Code

Every QR code contains these essential elements:

Finder Patterns: Three large squares in corners for orientation detection
Alignment Patterns: Smaller squares that help scanners read distorted codes
Timing Patterns: Alternating black/white lines between finder patterns
Format Information: Error correction level and mask pattern
Data Area: The actual encoded information
Quiet Zone: White border around the code (minimum 4 modules)

How QR Codes Work

QR codes encode data using a specific process that converts text into a scannable pattern.

Encoding Process

Data Analysis: Determine the most efficient encoding mode
Data Encoding: Convert characters to binary
Error Correction: Add Reed-Solomon error correction codes
Structure: Arrange data in the matrix pattern
Masking: Apply XOR mask for optimal scanning
Format/Version: Add metadata for decoder

QR Code Versions

QR codes come in 40 versions, each with increasing capacity:

Version	Size (modules)	Max Characters (L)
1	21 x 21	25 alphanumeric
10	57 x 57	395 alphanumeric
20	97 x 97	1,249 alphanumeric
40	177 x 177	4,296 alphanumeric

Higher versions = more data but larger codes and slower scanning.

Encoding Modes

QR codes automatically select the most efficient mode:

Numeric: Digits 0-9 (most efficient, ~3.3 bits per character)
Alphanumeric: 0-9, A-Z, space, $%*+-./: (~5.5 bits per character)
Byte: Any 8-bit data including UTF-8 (8 bits per character)
Kanji: Japanese characters (13 bits per character)

// Same URL encoded differently based on content
"12345678901234"        → Numeric mode (most compact)
"HTTPS://TOOLSDOCK.COM" → Alphanumeric mode
"https://toolsdock.com" → Byte mode (lowercase forces byte mode)

Data Types and Encoding

QR codes support various data formats through standardized URI schemes.

URL (Most Common)

https://toolsdock.com/generators/codes/qr-code-generator/?utm_source=qr

Plain Text

Any text content up to ~4,000 characters

WiFi Network

WIFI:T:WPA;S:NetworkName;P:Password123;H:false;;

Parameters:
T = Security type (WPA, WEP, nopass)
S = Network SSID
P = Password
H = Hidden network (true/false)

vCard (Contact Information)

BEGIN:VCARD
VERSION:3.0
N:Doe;John
FN:John Doe
ORG:Company Name
TEL:+1-555-123-4567
EMAIL:hello@toolsdock.com
URL:https://toolsdock.com
END:VCARD

Email

mailto:hello@toolsdock.com?subject=Hello&body=Message%20here

Phone Number

tel:+15551234567

SMS

sms:+15551234567?body=Hello%20World

Calendar Event

BEGIN:VEVENT
SUMMARY:Meeting Title
DTSTART:20240315T140000Z
DTEND:20240315T150000Z
LOCATION:Conference Room A
END:VEVENT

Geo Location

geo:40.7128,-74.0060

Bitcoin Payment

bitcoin:1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa?amount=0.001

Error Correction Levels

QR codes use Reed-Solomon error correction to remain scannable even when partially damaged or obscured.

Level	Recovery Capacity	Use Case
L (Low)	~7% damage	Clean environments, maximum data
M (Medium)	~15% damage	General purpose (default)
Q (Quartile)	~25% damage	Industrial, outdoor use
H (High)	~30% damage	Logos in center, harsh conditions

Pro Tip: Use Level H if you plan to add a logo in the center of your QR code. The high error correction compensates for the obscured data modules.

Trade-offs

Higher error correction = larger QR code for same data
Higher error correction = slower scanning
For clean digital displays, Level L is sufficient
For printed materials that may get damaged, use Level M or higher

Design Best Practices

Size Guidelines

Scan Distance	Minimum Size	Example Use
10 cm (4")	2 cm (0.8")	Business cards
30 cm (12")	3 cm (1.2")	Flyers, menus
1 m (3 ft)	10 cm (4")	Posters
5 m (16 ft)	50 cm (20")	Billboards

Rule of thumb: QR code size should be 1/10th of the expected scan distance.

Contrast Requirements

Dark foreground on light background works best
Minimum contrast ratio: 4:1 (higher is better)
Black on white has the best scan reliability
Avoid red or orange foregrounds (hard for some scanners)

Good combinations:
- Black on white (best)
- Dark blue on white
- Black on light yellow
- Dark green on white

Avoid:
- Light colors on light backgrounds
- Red on green (colorblind issues)
- Low contrast combinations
- Inverted (white on black) without testing

Adding Logos

Use error correction Level H
Keep logo under 30% of QR code area
Place logo exactly in center
Add white padding around logo
Test thoroughly with multiple devices

Quiet Zone

Always maintain a white border (quiet zone) around your QR code:

Minimum: 4 modules wide
Recommended: 10% of QR code size on each side
Don't place text or graphics touching the QR code

File Format Recommendations

Use Case	Format	Reason
Print (large)	SVG or PDF	Vector, scales infinitely
Print (fixed size)	PNG (300+ DPI)	Sharp edges, no compression artifacts
Web/Digital	PNG or SVG	Sharp, lossless
Documents	PNG	Universal compatibility

Never use JPEG for QR codes. Compression artifacts can make codes unscannable.

Common Use Cases

Marketing and Advertising

Print ads linking to landing pages
Product packaging with extended information
Event posters linking to ticket purchases
Billboard campaigns with trackable URLs

Retail and Payments

Mobile payment systems (Apple Pay, Google Pay)
Product information and reviews
Loyalty program enrollment
Digital receipts

Authentication and Security

Two-factor authentication (TOTP) setup
Secure document verification
Access control and ticketing
Cryptocurrency wallet addresses

Information Sharing

WiFi network credentials (hotels, cafes)
Business cards and contact sharing
Restaurant menus
Museum exhibits and tours

Development and Testing

App download links
Deep links for mobile apps
Debug URLs for testing
Configuration data transfer

Healthcare

Patient identification wristbands
Medication information
Vaccination certificates
Medical record access

Generating QR Codes Programmatically

JavaScript (Browser)

// Using QRCode.js library
const qrcode = new QRCode(document.getElementById("qrcode"), {
  text: "https://toolsdock.com",
  width: 256,
  height: 256,
  colorDark: "#000000",
  colorLight: "#ffffff",
  correctLevel: QRCode.CorrectLevel.M
});

Node.js

// Using qrcode package
const QRCode = require('qrcode');

// Generate as Data URL
const dataUrl = await QRCode.toDataURL('https://toolsdock.com');

// Generate as file
await QRCode.toFile('./qrcode.png', 'https://toolsdock.com', {
  width: 300,
  margin: 2,
  errorCorrectionLevel: 'M'
});

Python

# Using qrcode library
import qrcode

qr = qrcode.QRCode(
    version=1,
    error_correction=qrcode.constants.ERROR_CORRECT_M,
    box_size=10,
    border=4,
)
qr.add_data('https://toolsdock.com')
qr.make(fit=True)

img = qr.make_image(fill_color="black", back_color="white")
img.save("qrcode.png")

PHP

// Using phpqrcode library
include('phpqrcode/qrlib.php');

QRcode::png('https://toolsdock.com', 'qrcode.png', QR_ECLEVEL_M, 10, 2);

Dynamic QR Codes

For trackable, editable QR codes, encode a short URL that redirects:

// Instead of encoding the full URL:
https://toolsdock.com/very/long/campaign/url?utm_source=print

// Encode a short redirect URL:
https://toolsdock.com/

// Benefits:
// - Smaller QR code (easier to scan)
// - Track scan analytics
// - Change destination without reprinting
// - A/B test different landing pages

Tools and Resources

QR Code Generator

Create QR codes for URLs, text, WiFi, vCards, and more. Download as PNG or SVG.

Generate QR Code

Barcode Generator

Generate traditional 1D barcodes including Code 128, EAN-13, UPC-A, and more.

Generate Barcode

URL Encoder

Properly encode URLs before embedding in QR codes.

Encode URL

SVG to PNG Converter

Convert vector QR codes to high-resolution PNG for printing.

Convert SVG

Quick Reference: QR Code Data Formats

Type	Format
URL	`https://toolsdock.com`
Email	`mailto:hello@toolsdock.com?subject=Hi`
Phone	`tel:+15551234567`
SMS	`sms:+15551234567?body=Hello`
WiFi	`WIFI:T:WPA;S:SSID;P:pass;;`
Geo	`geo:40.7128,-74.0060`

Frequently Asked Questions

The maximum is 4,296 alphanumeric characters or 7,089 numeric digits (Version 40 with low error correction). However, larger codes are harder to scan. For URLs, keep content under 200 characters for reliable scanning. Use URL shorteners for long links.

QR code size should be about 1/10th of the expected scan distance. Business cards: 2cm (0.8"). Flyers: 3cm (1.2"). Posters at 1m distance: 10cm (4"). Billboards: 50cm (20") or larger. Always test with actual phones before final printing.

Yes, but use high error correction (Level H, 30% recovery) since the logo obscures data modules. Keep the logo under 30% of the QR code area, center it precisely, and add white padding around it. Always test thoroughly—logo QR codes fail more often.

Common problems: insufficient contrast (use dark on light), too small size, damaged/distorted print, insufficient quiet zone (white border), or encoding too much data. Test with multiple phones. Avoid red/orange colors which some scanners struggle with.

Static QR codes encode data directly and can't be changed after printing. Dynamic QR codes encode a short redirect URL that you control, allowing you to change the destination, track scans, and A/B test—without reprinting the code.

Use SVG or PDF for scalable vector printing at any size. Use PNG at 300+ DPI for fixed-size printing. Never use JPEG—compression artifacts can make codes unscannable. Vector formats are always preferred for professional printing.

Level M (15% recovery) is the default for general use. Use Level L (7%) for clean digital displays with maximum data. Use Level Q (25%) for outdoor/industrial use. Use Level H (30%) when adding a logo or expecting damage.

Yes, QR codes displayed on screens can be scanned by another phone. Ensure high contrast, adequate size, and avoid screen glare. This is common for ticket exchanges, mobile payment sharing, and app-to-app transfers.

Use a dynamic QR code with a redirect URL through a URL shortener or QR management platform. These services log each scan with timestamp, location, and device info. Add UTM parameters to your destination URL for Google Analytics tracking.