Generate QR Codes with an API: The Developer's Guide
Learn how to generate QR codes programmatically with an API. Complete developer guide covering use cases, customization, colors, sizes, and code examples in multiple languages.
By Christian Mesa·Updated Feb 27, 2026
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:
```
bitcoin:1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa?amount=0.001
```
### 2. WiFi Sharing
Encode WiFi credentials in a QR code that phones can scan to auto-connect:
```
WIFI:T:WPA;S:MyNetworkName;P:MyPassword123;;
```
### 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:
```
TICKET:EVT-2026-001:SEAT-A12:VIP
```
### 5. Contact Cards (vCard)
Share contact information instantly:
```
BEGIN:VCARD
VERSION:3.0
FN:John Developer
TEL:+1234567890
EMAIL:[email protected]
END:VCARD
```
## ToolCenter QR Code API
### API Endpoint
```
POST https://toolcenter.dev/api/v1/qr
```
### 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
```bash
# 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
```javascript
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
```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
```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:
```json
{
"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:
```bash
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:
```javascript
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
1. **Always use error correction** — Level M or higher for printed QR codes
2. **Test with multiple scanners** — Not all QR scanners handle custom colors well
3. **Include a quiet zone** — The white margin around the QR code is essential for scanning
4. **Keep data short** — Shorter data produces simpler, more scannable QR codes
5. **Use URL shorteners** for long URLs — Less data means a less dense QR code
6. **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 →](https://toolcenter.dev)**
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*Need help? Check the [API documentation](https://toolcenter.dev/docs) for detailed endpoint references and more examples.*