Are QR codes free to use commercially?

Yes, QR codes are an open standard and free to use for any purpose, including commercial applications. No licensing fees or royalties are required.

JavaScript QR Code Generator:

class QRCodeGenerator {
  constructor() {
    this.errorCorrectionLevels = {
      L: 'Low (~7% recovery)',
      M: 'Medium (~15% recovery)', 
      Q: 'Quartile (~25% recovery)',
      H: 'High (~30% recovery)'
    };
    
    this.qrTypes = {
      TEXT: 'text',
      URL: 'url',
      EMAIL: 'email',
      PHONE: 'phone',
      SMS: 'sms',
      WIFI: 'wifi',
      VCARD: 'vcard',
      EVENT: 'event',
      LOCATION: 'location'
    };
  }
  
  // Generate QR code for different data types
  generateQR(data, options = {}) {
    const defaultOptions = {
      size: 256,
      errorCorrectionLevel: 'M',
      foregroundColor: '#000000',
      backgroundColor: '#FFFFFF',
      margin: 4,
      format: 'PNG'
    };
    
    const config = { ...defaultOptions, ...options };
    
    try {
      // Format data based on type
      const qrData = this.formatData(data);
      
      // Generate QR code using library (e.g., qrious, qrcode.js)
      const qrCode = this.createQRCode(qrData, config);
      
      return {
        success: true,
        dataUrl: qrCode.toDataURL(),
        svg: config.format === 'SVG' ? qrCode.toSVG() : null,
        size: config.size,
        data: qrData,
        errorCorrectionLevel: config.errorCorrectionLevel
      };
    } catch (error) {
      return {
        success: false,
        error: error.message
      };
    }
  }
  
  // Format data for different QR code types
  formatData(data) {
    switch (data.type) {
      case this.qrTypes.URL:
        return this.ensureHttpProtocol(data.content);
        
      case this.qrTypes.EMAIL:
        return `mailto:${data.email}${data.subject ? '?subject=' + encodeURIComponent(data.subject) : ''}${data.body ? (data.subject ? '&' : '?') + 'body=' + encodeURIComponent(data.body) : ''}`;
        
      case this.qrTypes.PHONE:
        return `tel:${data.phone}`;
        
      case this.qrTypes.SMS:
        return `sms:${data.phone}${data.message ? '?body=' + encodeURIComponent(data.message) : ''}`;
        
      case this.qrTypes.WIFI:
        return `WIFI:T:${data.encryption || 'WPA'};S:${data.ssid};P:${data.password};H:${data.hidden ? 'true' : 'false'};;`;
        
      case this.qrTypes.VCARD:
        return this.generateVCard(data);
        
      case this.qrTypes.EVENT:
        return this.generateVEvent(data);
        
      case this.qrTypes.LOCATION:
        return `geo:${data.latitude},${data.longitude}${data.altitude ? ',' + data.altitude : ''}`;
        
      case this.qrTypes.TEXT:
      default:
        return data.content || data.text;
    }
  }
  
  // Generate vCard format for contact information
  generateVCard(data) {
    let vcard = 'BEGIN:VCARD\nVERSION:3.0\n';
    
    if (data.name) {
      vcard += `FN:${data.name}\n`;
      const nameParts = data.name.split(' ');
      if (nameParts.length >= 2) {
        vcard += `N:${nameParts[nameParts.length - 1]};${nameParts.slice(0, -1).join(' ')};;;\n`;
      }
    }
    
    if (data.organization) vcard += `ORG:${data.organization}\n`;
    if (data.title) vcard += `TITLE:${data.title}\n`;
    if (data.phone) vcard += `TEL:${data.phone}\n`;
    if (data.email) vcard += `EMAIL:${data.email}\n`;
    if (data.website) vcard += `URL:${data.website}\n`;
    
    if (data.address) {
      vcard += `ADR:;;${data.address.street || ''};${data.address.city || ''};${data.address.state || ''};${data.address.zip || ''};${data.address.country || ''}\n`;
    }
    
    vcard += 'END:VCARD';
    return vcard;
  }
  
  // Generate vEvent format for calendar events
  generateVEvent(data) {
    let vevent = 'BEGIN:VCALENDAR\nVERSION:2.0\nBEGIN:VEVENT\n';
    
    if (data.title) vevent += `SUMMARY:${data.title}\n`;
    if (data.description) vevent += `DESCRIPTION:${data.description}\n`;
    if (data.location) vevent += `LOCATION:${data.location}\n`;
    
    if (data.startDate) {
      vevent += `DTSTART:${this.formatDateForVEvent(data.startDate)}\n`;
    }
    
    if (data.endDate) {
      vevent += `DTEND:${this.formatDateForVEvent(data.endDate)}\n`;
    }
    
    // Generate unique ID
    vevent += `UID:${Date.now()}@qrcodegenerator.com\n`;
    
    vevent += 'END:VEVENT\nEND:VCALENDAR';
    return vevent;
  }
  
  // Format date for vEvent (YYYYMMDDTHHMMSSZ)
  formatDateForVEvent(date) {
    const d = new Date(date);
    return d.toISOString().replace(/[-:]/g, '').split('.')[0] + 'Z';
  }
  
  // Ensure URL has proper protocol
  ensureHttpProtocol(url) {
    if (!/^https?:\/\//.test(url)) {
      return 'https://' + url;
    }
    return url;
  }
  
  // Batch generate multiple QR codes
  batchGenerate(dataArray, options = {}) {
    const results = [];
    
    for (let i = 0; i < dataArray.length; i++) {
      const data = dataArray[i];
      const filename = data.filename || `qr_code_${i + 1}`;
      
      const result = this.generateQR(data, options);
      results.push({
        ...result,
        filename: filename,
        index: i
      });
    }
    
    return results;
  }
  
  // Download QR code as image
  downloadQR(dataUrl, filename = 'qrcode', format = 'PNG') {
    const link = document.createElement('a');
    link.download = `${filename}.${format.toLowerCase()}`;
    link.href = dataUrl;
    document.body.appendChild(link);
    link.click();
    document.body.removeChild(link);
  }
  
  // Create QR code with custom styling
  createStyledQR(data, style = {}) {
    const options = {
      size: style.size || 256,
      errorCorrectionLevel: style.errorCorrection || 'M',
      foregroundColor: style.foregroundColor || '#000000',
      backgroundColor: style.backgroundColor || '#FFFFFF',
      margin: style.margin || 4
    };
    
    // Add logo/image in center if provided
    if (style.logo) {
      options.logo = {
        src: style.logo,
        width: style.logoSize || 60,
        height: style.logoSize || 60,
        excavate: true // Remove QR modules behind logo
      };
    }
    
    return this.generateQR(data, options);
  }
  
  // Validate QR code data
  validateData(data) {
    const errors = [];
    
    switch (data.type) {
      case this.qrTypes.EMAIL:
        if (!data.email || !/^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(data.email)) {
          errors.push('Invalid email address');
        }
        break;
        
      case this.qrTypes.PHONE:
        if (!data.phone || !/^[+]?[\d\s\-()]+$/.test(data.phone)) {
          errors.push('Invalid phone number');
        }
        break;
        
      case this.qrTypes.URL:
        if (!data.content || !/^(https?:\/\/)?[\w\-._~:/?#[\]@!$&'()*+,;=]+\.[\w\-._~:/?#[\]@!$&'()*+,;=]+$/.test(data.content)) {
          errors.push('Invalid URL format');
        }
        break;
        
      case this.qrTypes.WIFI:
        if (!data.ssid) {
          errors.push('WiFi network name (SSID) is required');
        }
        break;
        
      case this.qrTypes.LOCATION:
        if (!data.latitude || !data.longitude) {
          errors.push('Latitude and longitude are required for location');
        }
        if (Math.abs(data.latitude) > 90 || Math.abs(data.longitude) > 180) {
          errors.push('Invalid GPS coordinates');
        }
        break;
    }
    
    return {
      valid: errors.length === 0,
      errors: errors
    };
  }
  
  // Get QR code information
  getQRInfo(dataUrl) {
    // This would typically use a QR code reader library
    return {
      estimated_version: 'Unknown',
      modules: 'Unknown',
      data_capacity: 'Unknown',
      error_correction: 'Unknown'
    };
  }
}

// Usage examples
const generator = new QRCodeGenerator();

// Generate URL QR code
const urlQR = generator.generateQR({
  type: 'url',
  content: 'https://www.example.com'
}, {
  size: 300,
  errorCorrectionLevel: 'M'
});

// Generate WiFi QR code
const wifiQR = generator.generateQR({
  type: 'wifi',
  ssid: 'MyNetwork',
  password: 'mypassword123',
  encryption: 'WPA',
  hidden: false
});

// Generate contact vCard
const contactQR = generator.generateQR({
  type: 'vcard',
  name: 'John Doe',
  phone: '+1234567890',
  email: 'john@example.com',
  organization: 'Example Corp',
  website: 'https://johndoe.com'
});

console.log('QR codes generated successfully!');