Key Information Extraction API

Overview

The Key Information Extraction API extracts structured information from invoices, certificates, forms and other documents. You can define custom JSON Schema to specify which fields to extract, and the model will intelligently identify and fill in the corresponding information from the image in JSON format.

It uses a unified JSON request format, accepting either URL references or base64-encoded image data.

Authentication

The API supports the following authentication method:

API Key: Pass your API key as a query parameter ?key=YOUR_API_KEY

Extract Structured Information from Image

Extract structured information from image files using intelligent recognition technology with custom JSON Schema.

Request

POST /api/key-information-extraction

Parameters:

Parameter	Type	Required	Description
document	object	Yes	Document object
document.type	string	Yes	Fixed value "image_url"
document.image_url	string	Yes	Image URL or base64 data
result_schema	object/string	Yes	JSON Schema defining fields to extract
filename	string	No	Filename (recommended for base64 data)
key	string	No	API key (query parameter, optional for logged-in users)

result_schema Notes:

Can be a JSON object or JSON string
Supports up to 3 levels of nesting
Only define keys (field names), keep values as empty strings
Supports array structures

Examples:

Using Image URL:

curl -X POST "https://llmocr.com/api/key-information-extraction?key=YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "document": {
      "type": "image_url",
      "image_url": "https://llmocr.com/invoice.jpg"
    },
    "result_schema": {
      "Seller Name": "",
      "Buyer Name": "",
      "Price Excluding Tax": "",
      "Invoice Code": ""
    }
  }'

Using Base64 Image Data:

curl -X POST "https://llmocr.com/api/key-information-extraction?key=YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "document": {
      "type": "image_url",
      "image_url": "data:image/jpeg;base64,/9j/4AAQSkZJRgABAQEA..."
    },
    "result_schema": {
      "Name": "",
      "ID Number": "",
      "Address": ""
    },
    "filename": "id-card.jpg"
  }'

Response

Parameters:

Parameter	Type	Description
id	string	Database record ID
filename	string	Filename
content	string	Extracted structured information (JSON string format)
format	string	Output format, fixed as "json"
timestamp	number	Processing completion timestamp
payload	string	API endpoint URL

Example:

{
  "id": "12345",
  "filename": "invoice.jpg",
  "content": "{\"Seller Name\":\"ABC Company Ltd\",\"Buyer Name\":\"John Doe\",\"Price Excluding Tax\":\"270000.00\",\"Invoice Code\":\"142011726001\"}",
  "format": "json",
  "timestamp": 1640995200000,
  "payload": "https://llmocr.com/api/key-information-extraction?key=YOUR_API_KEY"
}

LLMOCR

API Documentation

Quick Start

Overview

Authentication

Extract Structured Information from Image

Request

Response