Node.js Invoice Parsing API & OCR Wrapper

Why Invoice Parsing is Difficult

Open-source OCR engines fail on invoices due to their unstructured nature. Unlike fixed-format documents, invoice layouts vary between vendors, making template-based or regex-based approaches brittle and unscalable. Key challenges include accurately parsing multi-page tables with variable line items, handling low-quality scans suffering from skew and pixelation, and correctly interpreting diverse date and currency formats. Maintaining a custom parsing solution requires constant engineering effort to adapt to new vendor templates, leading to high maintenance costs and persistent accuracy issues.

Enterprise-Grade Extraction with StructOCR

StructOCR leverages pre-trained deep learning models specifically architected for financial documents, delivering a highly robust invoice parsing API. Our engine automatically pre-processes images to correct skew and lighting before extraction. Unlike basic engines that return a raw text dump, StructOCR provides a standardized JSON output with intelligently parsed fields like line items, merchant details, and validated totals. This eliminates the need for complex post-processing, facilitating seamless accounts payable automation. For full endpoint details and Node.js implementation guides, view our developer documentation.

Production Use Cases

• Accounts Payable Automation: Ingest vendor invoices automatically. Eliminate manual data entry, reduce processing time by 95%, and enable straight-through processing.
• Expense Management: Instantly capture merchant, date, and total amount from employee expense receipts and invoices for faster reimbursement cycles.
• Three-Way Matching: Extract PO numbers, line items, and quantities to automatically match invoices against purchase orders and goods receipt notes.

Implementation: Node.js API Wrapper

While our platform is a pure REST API, our official Node.js SDK wrapper simplifies integration. It handles file streams, Base64 encoding, and nested JSON parsing automatically.

Prerequisite: npm install structocr

const StructOCR = require('structocr');

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// Initialize the client with your API key for edge processing
const client = new StructOCR('YOUR_API_KEY_HERE');

async function parseInvoice() {
  // Supports PDFs, local image paths, Base64 strings, or image URLs
  const documentSource = './vendor_invoice.pdf';

  try {
    console.log(`Executing invoice parsing API for ${documentSource}...`);

    // The SDK handles file uploading or Base64 conversion under the hood
    const result = await client.scanInvoice(documentSource);

    if (result.success && result.data) {
      const data = result.data;
      console.log('✅ Parsing Successful!');
      
      // Access structured fields directly
      console.log(`Invoice #: ${data.invoice_number}`);
      console.log(`Date:      ${data.date} (Due: ${data.due_date})`);
      console.log(`Vendor:    ${data.merchant.name} (Tax ID: ${data.merchant.tax_id})`);
      
      // Financials
      console.log(`Total:     ${data.financials.total_amount} ${data.currency}`);
      console.log(`Tax:       ${data.financials.tax_amount}`);

      // Line Items (Table Data)
      console.log('\n--- Line Items ---');
      if (data.line_items && data.line_items.length > 0) {
        data.line_items.forEach(item => {
          console.log(`- ${item.description}: ${item.quantity} x ${item.unit_price} = ${item.amount}`);
        });
      }

    } else {
      console.error('❌ Parsing Failed:', result.error || 'Unknown Error');
    }
  } catch (error) {
    console.error('An unexpected error occurred:', error.message);
  }
}

parseInvoice();

Sample JSON Output

The parsing API returns a normalized JSON object, regardless of the input document format or quality.

{
  "success": true,
  "data": {
    "type": "invoice",
    "invoice_number": "INV-2026-001",
    "date": "2026-01-15",
    "due_date": "2026-02-15",
    "currency": "USD",
    "merchant": {
      "name": "AWS Web Services",
      "address": "410 Terry Ave N, Seattle, WA",
      "tax_id": "EIN-12-3456789",
      "iban": null
    },
    "customer": {
      "name": "Acme Corp Inc.",
      "tax_id": "987654321"
    },
    "financials": {
      "subtotal": 100,
      "tax_amount": 10,
      "total_amount": 110
    },
    "line_items": [
      {
        "description": "EC2 Instance Usage",
        "quantity": 1,
        "unit_price": 80,
        "amount": 80
      },
      {
        "description": "S3 Storage",
        "quantity": 1,
        "unit_price": 20,
        "amount": 20
      }
    ]
  }
}