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10 Powerful PDF API Use Cases Every Developer Should Know (2025)

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OnlyDocs Team
OnlyDocs Team

10 Powerful PDF API Use Cases Every Developer Should Know (2025)

Thinking about integrating PDF functionality into your app? A PDF API can automate document generation, conversions, and processing—saving you weeks of development time and thousands in licensing costs.

This guide covers 10 real-world use cases with code examples using OnlyDocs API ($29.99/month unlimited).

Use Case 1: SaaS Invoice Generation

The Problem: Your SaaS app needs to generate thousands of branded invoices monthly.

Traditional Approach:

  • Build PDF generation from scratch (weeks of work)
  • Or use expensive Adobe API ($0.05/invoice = $5,000/month for 100k invoices)

OnlyDocs Solution: $29.99/month, unlimited invoices

// Generate invoice from HTML template
async function generateInvoice(invoiceData) {
  const html = `
    <!DOCTYPE html>
    <html>
    <head>
      <style>
        body { font-family: Arial; }
        .header { background: #4F46E5; color: white; padding: 20px; }
        .invoice-table { width: 100%; border-collapse: collapse; }
        .invoice-table td { padding: 10px; border-bottom: 1px solid #ddd; }
      </style>
    </head>
    <body>
      <div class="header">
        <h1>INVOICE #${invoiceData.invoiceNumber}</h1>
      </div>
      <table class="invoice-table">
        <tr>
          <td><strong>Bill To:</strong></td>
          <td>${invoiceData.customer}</td>
        </tr>
        <tr>
          <td><strong>Amount Due:</strong></td>
          <td>$${invoiceData.amount}</td>
        </tr>
      </table>
    </body>
    </html>
  `;

  const response = await fetch('https://api.onlydocs.net/v1/convert/html-to-pdf', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${process.env.ONLYDOCS_API_KEY}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      html,
      options: {
        format: 'A4',
        margin: { top: '20mm', bottom: '20mm' }
      }
    })
  });

  const result = await response.json();
  return result.data.pdfBase64; // Send to customer
}

ROI:

  • 100k invoices/month
  • OnlyDocs: $29.99/month
  • Adobe: $5,000/month
  • Savings: $59,881/year

Use Case 2: E-Learning Certificate Generator

The Problem: Online course platform needs to generate completion certificates for students.

Requirements:

  • Custom branding per course
  • Student name/date personalization
  • Download or email delivery

Solution:

async function generateCertificate(studentName, courseName, completionDate) {
  const html = `
    <!DOCTYPE html>
    <html>
    <head>
      <style>
        body {
          text-align: center;
          font-family: 'Georgia', serif;
          padding: 50px;
        }
        .certificate {
          border: 10px solid gold;
          padding: 40px;
        }
        h1 { font-size: 48px; color: #1a1a1a; }
        .student { font-size: 36px; font-weight: bold; color: #4F46E5; }
      </style>
    </head>
    <body>
      <div class="certificate">
        <h1>Certificate of Completion</h1>
        <p>This certifies that</p>
        <p class="student">${studentName}</p>
        <p>has successfully completed</p>
        <p><strong>${courseName}</strong></p>
        <p>on ${completionDate}</p>
      </div>
    </body>
    </html>
  `;

  const response = await fetch('https://api.onlydocs.net/v1/convert/html-to-pdf', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${process.env.ONLYDOCS_API_KEY}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({ html })
  });

  const result = await response.json();

  // Save to database and email to student
  await saveAndEmailCertificate(studentName, result.data.pdfBase64);

  return result.data.pdfBase64;
}

Use Case 3: Contract Management System

The Problem: Legal tech platform needs to merge contract templates with client data and collect signatures.

Workflow:

  1. Generate contract from template
  2. Fill in client/date variables
  3. Send for signature
  4. Archive signed version

Solution:

async function generateContract(templateId, clientData) {
  // Step 1: Fetch template HTML
  const template = await getContractTemplate(templateId);

  // Step 2: Replace variables
  const html = template
    .replace('{{CLIENT_NAME}}', clientData.name)
    .replace('{{START_DATE}}', clientData.startDate)
    .replace('{{RATE}}', clientData.rate)
    .replace('{{SERVICES}}', clientData.services);

  // Step 3: Generate PDF
  const response = await fetch('https://api.onlydocs.net/v1/convert/html-to-pdf', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${process.env.ONLYDOCS_API_KEY}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({ html })
  });

  const result = await response.json();

  // Step 4: Store and send for signature
  const contractId = await saveContract(result.data.pdfBase64, clientData);
  await sendForSignature(contractId, clientData.email);

  return contractId;
}

Use Case 4: Receipt OCR for Expense Tracking

The Problem: Expense management app needs to extract data from scanned receipts.

Traditional Approach: Build ML model (months) or use Google Vision API ($1.50/1000 images)

OnlyDocs Solution: OCR API included at $29.99/month

async function processReceipt(receiptImageBase64) {
  // Step 1: Convert image to PDF (if needed)
  const pdfResponse = await fetch('https://api.onlydocs.net/v1/editor/images-to-pdf', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${process.env.ONLYDOCS_API_KEY}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({ images: [receiptImageBase64] })
  });

  const pdf = await pdfResponse.json();

  // Step 2: Perform OCR
  const ocrResponse = await fetch('https://api.onlydocs.net/v1/convert/ocr', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${process.env.ONLYDOCS_API_KEY}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      pdfBase64: pdf.data.pdfBase64,
      language: 'eng'
    })
  });

  const ocr = await ocrResponse.json();

  // Step 3: Extract data using regex
  const text = ocr.data.text;
  const total = text.match(/Total:?\s*\$?([\d,.]+)/i)?.[1];
  const date = text.match(/(\d{1,2}\/\d{1,2}\/\d{2,4})/)?.[1];
  const merchant = text.split('\n')[0]; // Usually first line

  return { total, date, merchant, fullText: text };
}

ROI:

  • 10k receipts/month
  • Google Vision: $15/month
  • OnlyDocs: $29.99/month (includes OCR + all other features)
  • Still cheaper with way more features

Use Case 5: Automated Report Generation

The Problem: Analytics dashboard needs to generate weekly PDF reports for clients.

Solution: Convert chart data to images, combine with HTML report

const puppeteer = require('puppeteer');

async function generateWeeklyReport(clientId, metrics) {
  // Step 1: Generate charts as images
  const chartImages = await generateCharts(metrics);

  // Step 2: Build HTML report
  const html = `
    <!DOCTYPE html>
    <html>
    <body>
      <h1>Weekly Analytics Report</h1>
      <p>Client: ${clientId}</p>
      <p>Week of: ${new Date().toLocaleDateString()}</p>

      <h2>Traffic Overview</h2>
      <img src="data:image/png;base64,${chartImages.traffic}" width="600"/>

      <h2>Conversions</h2>
      <img src="data:image/png;base64,${chartImages.conversions}" width="600"/>

      <h2>Summary</h2>
      <ul>
        <li>Total Visitors: ${metrics.visitors.toLocaleString()}</li>
        <li>Conversion Rate: ${metrics.conversionRate}%</li>
        <li>Revenue: $${metrics.revenue.toLocaleString()}</li>
      </ul>
    </body>
    </html>
  `;

  // Step 3: Convert to PDF
  const response = await fetch('https://api.onlydocs.net/v1/convert/html-to-pdf', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${process.env.ONLYDOCS_API_KEY}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({ html, options: { format: 'Letter' } })
  });

  const result = await response.json();

  // Step 4: Email to client
  await emailReport(clientId, result.data.pdfBase64);

  return result.data.pdfBase64;
}

Use Case 6: Document Archive Compression

The Problem: Legacy system has millions of large scanned PDFs eating up storage.

ROI: Compress PDFs by 60-80% without quality loss

async function compressArchive() {
  const oldPDFs = await getAllArchivedPDFs(); // Get from S3/database

  for (const pdf of oldPDFs) {
    const pdfBase64 = pdf.data.toString('base64');

    // Compress PDF
    const response = await fetch('https://api.onlydocs.net/v1/editor/compress', {
      method: 'POST',
      headers: {
        'Authorization': `Bearer ${process.env.ONLYDOCS_API_KEY}`,
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({
        pdfBase64,
        compressionLevel: 'high' // 'low', 'medium', or 'high'
      })
    });

    const result = await response.json();
    const compressed = Buffer.from(result.data.pdfBase64, 'base64');

    // Calculate savings
    const originalSize = pdf.data.length;
    const compressedSize = compressed.length;
    const savings = ((originalSize - compressedSize) / originalSize * 100).toFixed(1);

    console.log(`Compressed ${pdf.id}: ${originalSize} → ${compressedSize} (${savings}% savings)`);

    // Save back to storage
    await updatePDF(pdf.id, compressed);
  }
}

Real savings:

  • 1TB storage → 300GB (70% reduction)
  • AWS S3 Standard: $23/TB/month
  • Before: $23/month
  • After: $6.90/month
  • Savings: $193.20/year in storage alone

Use Case 7: Form Data Extraction

The Problem: Insurance company receives 1000s of filled PDF forms daily that need data entry.

Solution: Extract form field data automatically

async function extractFormData(pdfBase64) {
  // Extract all text
  const response = await fetch('https://api.onlydocs.net/v1/editor/extract-text', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${process.env.ONLYDOCS_API_KEY}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({ pdfBase64 })
  });

  const result = await response.json();
  const text = result.data.text;

  // Parse extracted text for key fields
  const formData = {
    name: text.match(/Name:?\s*([^\n]+)/i)?.[1]?.trim(),
    email: text.match(/([a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,})/)?.[1],
    phone: text.match(/Phone:?\s*([\d\-\(\)\s]+)/i)?.[1]?.trim(),
    address: text.match(/Address:?\s*([^\n]+)/i)?.[1]?.trim(),
  };

  // Save to database
  await saveFormSubmission(formData);

  return formData;
}

ROI:

  • 1000 forms/day
  • Manual data entry: 5 min/form = 83 hours/day
  • At $20/hour: $1,660/day = $49,800/month
  • OnlyDocs API: $29.99/month
  • Savings: $49,770/month

Use Case 8: Multi-Language Document Converter

The Problem: International company needs to convert documents between formats for different teams.

Solution: Batch convert PDFs to Word (for editing), Excel (for data), or images (for web)

async function convertDocumentBatch(pdfs, targetFormat) {
  const endpoints = {
    'word': '/api/v1/convert/pdf-to-docx',
    'excel': '/api/v1/convert/pdf-to-xlsx',
    'image': '/api/v1/convert/pdf-to-image',
    'html': '/api/v1/convert/pdf-to-html'
  };

  const results = await Promise.all(
    pdfs.map(async (pdfBase64) => {
      const response = await fetch(`https://api.onlydocs.net${endpoints[targetFormat]}`, {
        method: 'POST',
        headers: {
          'Authorization': `Bearer ${process.env.ONLYDOCS_API_KEY}`,
          'Content-Type': 'application/json'
        },
        body: JSON.stringify({ pdfBase64 })
      });

      return await response.json();
    })
  );

  return results;
}

// Usage
const pdfs = await getPendingConversions();
const converted = await convertDocumentBatch(pdfs, 'word');

Use Case 9: Document Compression at Scale

The Problem: SaaS platform generates large PDF reports, causing slow downloads and high storage costs.

Solution: Automatically compress all generated PDFs

async function generateAndCompressReport(reportData) {
  // Generate report from template
  const reportPdf = await generateReport(reportData);

  // Compress for storage and download
  const response = await fetch('https://api.onlydocs.net/v1/editor/compress', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${process.env.ONLYDOCS_API_KEY}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      pdfBase64: reportPdf,
      compressionLevel: 'high', // 'low', 'medium', 'high'
      optimizeImages: true,
      removeDuplicates: true
    })
  });

  const result = await response.json();

  // Result typically 50-80% smaller
  console.log(`Original: ${reportPdf.length} bytes`);
  console.log(`Compressed: ${result.data.pdfBase64.length} bytes`);
  console.log(`Savings: ${((1 - result.data.pdfBase64.length / reportPdf.length) * 100).toFixed(1)}%`);

  // Store compressed version
  await storePDF(result.data.pdfBase64);

  return result.data.pdfBase64;
}

// Batch compression for existing documents
async function compressExistingDocuments() {
  const largeDocuments = await findLargeDocuments(); // > 5MB

  const results = await Promise.all(
    largeDocuments.map(async (doc) => {
      const compressed = await fetch('https://api.onlydocs.net/v1/editor/compress', {
        method: 'POST',
        headers: {
          'Authorization': `Bearer ${process.env.ONLYDOCS_API_KEY}`,
          'Content-Type': 'application/json'
        },
        body: JSON.stringify({
          pdfBase64: doc.pdfBase64,
          compressionLevel: 'high'
        })
      }).then(r => r.json());

      return {
        id: doc.id,
        originalSize: doc.size,
        newSize: Buffer.from(compressed.data.pdfBase64, 'base64').length,
        pdf: compressed.data.pdfBase64
      };
    })
  );

  // Save compressed versions
  for (const result of results) {
    await updateDocument(result.id, result.pdf);
    console.log(`Compressed ${result.id}: ${result.originalSize} → ${result.newSize} bytes`);
  }

  const totalSaved = results.reduce((sum, r) => sum + (r.originalSize - r.newSize), 0);
  console.log(`Total storage saved: ${(totalSaved / 1024 / 1024).toFixed(2)} MB`);
}

Use Case 10: Website Screenshot to PDF

The Problem: Compliance tool needs to archive web pages as PDFs for legal records.

Solution: Convert URLs to PDFs automatically

async function archiveWebPage(url) {
  const response = await fetch('https://api.onlydocs.net/v1/convert/url-to-pdf', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${process.env.ONLYDOCS_API_KEY}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      url,
      options: {
        fullPage: true, // Capture entire page
        waitUntil: 'networkidle', // Wait for page to fully load
        format: 'A4'
      }
    })
  });

  const result = await response.json();

  // Add metadata
  const withMetadata = await fetch('https://api.onlydocs.net/v1/editor/metadata', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${process.env.ONLYDOCS_API_KEY}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({
      pdfBase64: result.data.pdfBase64,
      metadata: {
        title: `Archive of ${url}`,
        author: 'Compliance Bot',
        subject: 'Web Archive',
        keywords: `archive, ${new Date().toISOString()}`
      }
    })
  });

  return await withMetadata.json();
}

Common Integration Patterns

Pattern 1: Queue-Based Processing

const Bull = require('bull');
const pdfQueue = new Bull('pdf-generation');

// Add job to queue
pdfQueue.add({ type: 'invoice', data: invoiceData });

// Process jobs
pdfQueue.process(async (job) => {
  const { type, data } = job.data;

  const response = await fetch('https://api.onlydocs.net/v1/convert/html-to-pdf', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${process.env.ONLYDOCS_API_KEY}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({ html: generateHTML(type, data) })
  });

  const result = await response.json();
  await savePDF(result.data.pdfBase64);
});

Pattern 2: Webhook Callbacks

// Request with callback URL
const response = await fetch('https://api.onlydocs.net/v1/async/html-to-pdf', {
  method: 'POST',
  headers: {
    'Authorization': `Bearer ${process.env.ONLYDOCS_API_KEY}`,
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    html: largeHTML,
    callbackUrl: 'https://myapp.com/api/pdf-completed'
  })
});

// Handle callback
app.post('/api/pdf-completed', (req, res) => {
  const { jobId, status, result } = req.body;

  if (status === 'completed') {
    const pdfBase64 = result.pdfBase64;
    await processPDF(pdfBase64);
  }

  res.json({ received: true });
});

Pattern 3: Batch Processing with Rate Limiting

const pLimit = require('p-limit');
const limit = pLimit(10); // 10 concurrent requests

async function processBatch(items) {
  const results = await Promise.all(
    items.map(item =>
      limit(async () => {
        const response = await fetch('https://api.onlydocs.net/v1/editor/merge', {
          method: 'POST',
          headers: {
            'Authorization': `Bearer ${process.env.ONLYDOCS_API_KEY}`,
            'Content-Type': 'application/json'
          },
          body: JSON.stringify({ pdfs: item.pdfs })
        });
        return await response.json();
      })
    )
  );

  return results;
}

Cost Comparison Across Use Cases

Use Case Monthly Volume OnlyDocs Adobe Savings
Invoice Gen 100k PDFs $29.99 $5,000 $59,881/yr
Certificates 50k PDFs $29.99 $2,500 $29,641/yr
OCR Processing 10k scans $29.99 $500 $5,641/yr
Compression 1M PDFs $29.99 $50,000 $599,881/yr
Report Gen 5k reports $29.99 $250 $2,641/yr

Total potential savings: $697,685/year across all use cases

Getting Started

  1. Sign up: Visit onlydocs.net/pricing
  2. Upgrade to Business: $29.99/month (API requires Business tier)
  3. Generate API Key: Dashboard → Settings → API Keys
  4. Start building: Unlimited requests with Business subscription
  5. Deploy: 100 requests/minute rate limit

API Resources

The Bottom Line

A PDF API unlocks massive automation potential. Whether you're:

  • Generating invoices
  • Processing scanned documents
  • Creating reports
  • Managing contracts
  • Archiving web pages

OnlyDocs API gives you enterprise capabilities at $29.99/month unlimited—saving you 94-99% compared to Adobe or PDFtron.

Start building today and see why developers are switching to OnlyDocs.

Keywords: PDF API use cases, document automation, invoice generation API, OCR API, PDF processing, developer tools, OnlyDocs API, PDF API examples