Generate QR Codes with an API: The Developer's Guide

QR codes are everywhere — from restaurant menus to payment systems, event tickets to WiFi sharing. As a developer, you’ll eventually need to generate QR codes programmatically, and using a QR code API is the fastest, most reliable way to do it.

In this guide, we’ll show you how to generate QR codes using the ToolCenter QR API, including customization options, real-world use cases, and code examples in multiple languages.

Why Use a QR Code API?

While there are QR code libraries for every programming language, a hosted API offers several advantages:

No dependencies — No need to install image processing libraries
Consistent output — Same quality across all platforms
Customization — Colors, sizes, error correction levels, and more
CDN delivery — Generated QR codes served from edge locations
No server-side rendering — Offload image generation to the API
Integration simplicity — A single HTTP request generates your QR code

Real-World Use Cases

1. Payment Links

Mobile payment apps like Venmo, CashApp, and cryptocurrency wallets use QR codes to encode payment addresses:

Encode WiFi credentials in a QR code that phones can scan to auto-connect:

3. Product Links and Marketing

Link physical products to digital experiences — scan to open product pages, reviews, or manuals.

4. Event Tickets

Generate unique QR codes for each ticket that can be validated at the door:

5. Contact Cards (vCard)

Share contact information instantly:

ToolCenter QR Code API

API Endpoint

Parameters

Parameter	Type	Required	Description
`data`	string	Yes	Content to encode in the QR code
`size`	integer	No	Image size in pixels (default: 300)
`format`	string	No	Output format: png, svg, jpg (default: png)
`fg_color`	string	No	Foreground color hex (default: #000000)
`bg_color`	string	No	Background color hex (default: #FFFFFF)
`error_correction`	string	No	Error correction level: L, M, Q, H (default: M)
`margin`	integer	No	Quiet zone margin in modules (default: 4)

Error Correction Levels

QR codes have built-in error correction, allowing them to be read even if partially damaged:

Level	Recovery	Best For
L (Low)	~7%	Clean digital displays
M (Medium)	~15%	General use (recommended)
Q (Quartile)	~25%	Printed materials
H (High)	~30%	QR codes with logos overlay

Code Examples

cURL

# Simple QR code
curl -X POST "https://toolcenter.dev/api/v1/qr" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "data": "https://example.com",
    "size": 400,
    "format": "png"
  }' \
  --output qrcode.png

# Custom colored QR code
curl -X POST "https://toolcenter.dev/api/v1/qr" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "data": "https://example.com",
    "size": 500,
    "format": "png",
    "fg_color": "#1a73e8",
    "bg_color": "#ffffff",
    "error_correction": "H"
  }' \
  --output qrcode-branded.png

Node.js

const ToolCenter = require('devtoolbox-sdk');
const fs = require('fs');

const client = new ToolCenter('YOUR_API_KEY');

// Generate a simple QR code
async function generateQR() {
  const qr = await client.qr({
    data: 'https://example.com',
    size: 400,
    format: 'png'
  });

  fs.writeFileSync('qrcode.png', qr);
  console.log('QR code generated!');
}

// Generate WiFi QR code
async function generateWiFiQR(ssid, password, encryption = 'WPA') {
  const wifiString = `WIFI:T:${encryption};S:${ssid};P:${password};;`;
  
  const qr = await client.qr({
    data: wifiString,
    size: 500,
    fgColor: '#2d3748',
    bgColor: '#ffffff',
    errorCorrection: 'H'
  });

  fs.writeFileSync('wifi-qr.png', qr);
  console.log(`WiFi QR for "${ssid}" generated!`);
}

// Generate payment QR code
async function generatePaymentQR(address, amount) {
  const qr = await client.qr({
    data: `bitcoin:${address}?amount=${amount}`,
    size: 300,
    errorCorrection: 'H'
  });

  fs.writeFileSync('payment-qr.png', qr);
}

generateQR();
generateWiFiQR('MyNetwork', 'SecurePass123');

Python

from devtoolbox import ToolCenter

client = ToolCenter("YOUR_API_KEY")

# Generate a simple QR code
qr = client.qr(
    data="https://example.com",
    size=400,
    format="png"
)

with open("qrcode.png", "wb") as f:
    f.write(qr)
print("QR code generated!")

# Generate vCard QR code
vcard = """BEGIN:VCARD
VERSION:3.0
FN:Jane Developer
ORG:ToolCenter
TEL:+1234567890
EMAIL:[email protected]
URL:https://devtoolbox.com
END:VCARD"""

qr = client.qr(
    data=vcard,
    size=500,
    error_correction="Q"
)

with open("contact-qr.png", "wb") as f:
    f.write(qr)
print("Contact QR code generated!")

PHP

use ToolCenter\Client;

$client = new Client('YOUR_API_KEY');

// Generate a simple QR code
$qr = $client->qr([
    'data' => 'https://example.com',
    'size' => 400,
    'format' => 'png',
]);

file_put_contents('qrcode.png', $qr);

// Generate event ticket QR code
$ticketData = json_encode([
    'event' => 'DevConf 2026',
    'ticket_id' => 'TCK-001-VIP',
    'seat' => 'A12',
    'holder' => 'John Doe',
]);

$qr = $client->qr([
    'data' => $ticketData,
    'size' => 300,
    'error_correction' => 'H',
    'fg_color' => '#1a1a2e',
    'bg_color' => '#ffffff',
]);

file_put_contents('ticket-qr.png', $qr);
echo "Ticket QR generated!\n";

Customization Tips

Brand Colors

Use your brand colors for the foreground, but ensure sufficient contrast:

{
  "fg_color": "#1a73e8",
  "bg_color": "#ffffff"
}

Important: Always maintain high contrast between foreground and background. Dark foreground on light background works best. Avoid light foreground colors as many scanners struggle with them.

Choosing the Right Size

Use Case	Recommended Size
Web display	200-300px
Print (flyers, posters)	400-600px
Large format (billboards)	800-1000px
Favicon/icon	100-150px

SVG for Scalability

For print materials or responsive web displays, use SVG format:

curl -X POST "https://toolcenter.dev/api/v1/qr" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"data": "https://example.com", "format": "svg"}' \
  --output qrcode.svg

SVG QR codes scale infinitely without losing quality — perfect for print.

Bulk QR Code Generation

Need to generate hundreds of QR codes? Use ToolCenter’s bulk endpoint:

const ToolCenter = require('devtoolbox-sdk');
const client = new ToolCenter('YOUR_API_KEY');

const urls = [
  'https://example.com/product/1',
  'https://example.com/product/2',
  'https://example.com/product/3',
  // ... hundreds more
];

const results = await client.bulk('qr', urls.map(url => ({
  data: url,
  size: 400,
  format: 'png'
})));

console.log(`Generated ${results.length} QR codes`);

Best Practices

Always use error correction — Level M or higher for printed QR codes
Test with multiple scanners — Not all QR scanners handle custom colors well
Include a quiet zone — The white margin around the QR code is essential for scanning
Keep data short — Shorter data produces simpler, more scannable QR codes
Use URL shorteners for long URLs — Less data means a less dense QR code
Provide fallback — Always show the URL or data as text near the QR code

Pricing

QR code generation is included in all ToolCenter plans:

Plan	Price	Monthly Requests
Free	$0	100
Starter	$9/mo	5,000
Pro	$29/mo	25,000
Business	$79/mo	100,000

All plans include QR codes, screenshots, PDFs, OG images, and metadata extraction.

Conclusion

Generating QR codes with the ToolCenter QR API is simple, fast, and reliable. Whether you need a single QR code for your WiFi or thousands for event tickets, the API handles it all with full customization support.

Combined with ToolCenter’s other tools — screenshots, PDFs, OG images, and metadata extraction — you have a complete developer toolkit at your fingertips.

Generate Your First QR Code →

Need help? Check the API documentation for detailed endpoint references and more examples.

Why Use a QR Code API?#

Real-World Use Cases#

1. Payment Links#

2. WiFi Sharing#

3. Product Links and Marketing#

4. Event Tickets#

5. Contact Cards (vCard)#

ToolCenter QR Code API#

API Endpoint#

Parameters#

Error Correction Levels#

Code Examples#

cURL#

Node.js#

Python#

PHP#

Customization Tips#

Brand Colors#

Choosing the Right Size#

SVG for Scalability#

Bulk QR Code Generation#

Best Practices#

Pricing#

Conclusion#