Invoice OCR

Automate your Accounts Payable (AP) and expense workflows with our intelligent Invoice OCR API. Unlike traditional templates, our AI understands the semantic structure of documents, allowing it to extract line items, tax breakdowns, and vendor details from any invoice layout. Perfect for ERP integrations, bookkeeping software, and receipt scanning apps.

Endpoint

POSThttps://api.structocr.com/v1/invoice

Request Parameters

Note: Currently supports image inputs (JPG, PNG). For multi-page PDFs, we recommend converting the first page to an image before sending.

Parameter	In	Required	Description
x-api-key	Header	Required	Your unique API key generated from the dashboard.
Content-Type	Header	Required	Must be set to `application/json`.
img	Body (JSON)	Required	The Base64 encoded string of the invoice/receipt image. Supports standard Data URI scheme Supports raw Base64 strings Max file size: 4.5MB Formats: JPG, PNG, WebP

Response Schema

The API returns a nested JSON object designed for accounting systems. Fields are grouped by context (`merchant`, `customer`, `financials`, `line_items`).

Field	Description
Root Metadata
type	Document type, typically returns 'invoice' or 'receipt'.
invoice_number	Unique identifier/reference number of the document.
date	Invoice issue date (YYYY-MM-DD).
due_date	Payment due date (YYYY-MM-DD), helpful for cash flow management.
currency	ISO 4217 currency code (e.g., 'USD', 'EUR').
Merchant (Vendor)
merchant.name	Name of the supplier or vendor.
merchant.tax_id	Tax registration number (VAT, GST, EIN, ABN).
merchant.iban	International Bank Account Number (Critical for EU/UK invoices).
Financials
financials.total_amount	The final total amount due (including tax).
financials.tax_amount	Total tax amount extracted from the summary.
financials.subtotal	Net amount before tax.
Line Items (Array)
line_items[].description	Description of the product or service.
line_items[].quantity	Count or hours.
line_items[].unit_price	Price per unit.
line_items[].amount	Line total (Quantity * Unit Price).

Code Examples

Request Implementation

curl -X POST https://api.structocr.com/v1/invoice \
  -H "Content-Type: application/json" \
  -H "x-api-key: YOUR_API_KEY" \
  -d '{
    "img": "data:image/jpeg;base64,/9j/4AAQSkZJRg..."
  }'

Success Response (200 OK)

JSON EXAMPLE

{
  "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
      }
    ]
  }
}

Error Responses

400 Bad Request

{
  "status": 400,
  "code": "INVALID_REQUEST_FORMAT",  
  // or "INVALID_JSON", "INVALID_BASE64_FORMAT"
  "message":"The image data in 'img' field is malformed. Please check for illegal characters (spaces, newlines) or incorrect Base64 encoding."
}

402 Payment Required

Each successful invoice extraction costs 3 credits.

{
  "success": false,
  "error": "INSUFFICIENT_CREDITS",
  "message": "Your account balance is insufficient to complete this operation."
}

422 Unprocessable Entity

Returned if the AI safety filter blocks the content.

{
  "success": false,
  "error": "CONTENT_POLICY_VIOLATION",
  "message": "The document content could not be processed due to safety policies."
}

503 Service Unavailable

{
  "success": false,
  "error": "SYSTEM_BUSY",
  "message": "StructOCR is currently processing a high volume of requests..."
}

Status Code Definitions

Code	Error Code	Description
200	SUCCESS	Recognition success
400	INVALID_REQUEST_FORMAT	Invalid payload or corrupted Base64. Ensure the image string has no whitespace, newlines, or illegal characters.
402	INSUFFICIENT_CREDITS	Insufficient credits (Cost: 3/req)
413	FILE_TOO_LARGE	Decoded image exceeds 4.5MB
422	CONTENT_POLICY_VIOLATION	AI safety/policy block
503	SYSTEM_BUSY	API Rate limit reached