🤖 Extract Invoice

Introduction

This API allows users to send an invoice via a POST request, and n8n will automatically evaluate and rate the invoice. The API processes the content and returns an analysis based on the provided model.

Extract Invoice

Endpoint

Use the following endpoint to submit the invoice for analytic:

POST https://n8n.lchatai.com/execute/invoice-analytics

Headers

The API requires the following headers:

• X-N8N-API-KEY - Your n8n API key for authentication
• Content-Type: multipart/form-data

Request Parameters

The API expects the following parameters as multipart/form-data fields:

• model (string) - The AI model to use. Accepted values:

  Provider	Models
  OpenAI	gpt-4o, gpt-4o-mini, gpt-4-turbo, gpt-3.5-turbo, gpt-4.1, gpt-4.1-mini, gpt-4.1-nano, gpt-5.2, gpt-5.2-pro, gpt-5, gpt-5-mini, gpt-5-nano
  Gemini	gemini-2.5-flash, gemini-2.5-pro, gemini-2.5-flash-lite, gemini-3-flash-preview, gemini-3.1-pro-preview
  Claude	claude-sonnet-4-6, claude-opus-4-6, claude-opus-4-5-20251101, claude-haiku-4-5-20251001, claude-sonnet-4-5-20250929, claude-opus-4-1-20250805, claude-opus-4-20250514, claude-sonnet-4-20250514

• prompt (string) - The specific prompt to provide for the invoice evaluation.

• llmKey (string) - Your API key for the selected model.

• content (string) - The invoice text to be analyzed. Use this field when submitting plain text. Leave empty ("") when uploading a file via the file field.

• file (file) - A PDF or document file containing the invoice. Use this field when submitting a file. Leave empty ("") when using the content field.

warning

Exactly one of content or file must be provided per request. If you are sending text, pass file="". If you are uploading a file, pass content="".

Example Request

Bash

Text Content

curl --location 'https://n8n.lchatai.com/execute/invoice-analytics' \
  --header 'X-N8N-API-KEY: ey*********' \
  --form 'model="gpt-4o-mini"' \
  --form 'prompt="..."' \
  --form 'content="Invoice text content here..."' \
  --form 'llmKey="sk-proj-ERa23*******"' \
  --form 'file=""'

File Upload

curl --location 'https://n8n.lchatai.com/execute/invoice-analytics' \
  --header 'X-N8N-API-KEY: ey*********' \
  --form 'model="gpt-4o-mini"' \
  --form 'prompt="..."' \
  --form 'content=""' \
  --form 'llmKey="sk-proj-ERa23*******"' \
  --form 'file=@"/path/to/invoice.pdf"'

Javascript

Text Content

// Text Content mode
const formData = new FormData();
formData.append('model', 'gpt-4o-mini');
formData.append('prompt', '...');
formData.append('content', 'Invoice text content here...');
formData.append('llmKey', 'sk-proj-ERa23*******');
formData.append('file', '');

fetch('https://n8n.lchatai.com/execute/invoice-analytics', {
  method: 'POST',
  headers: { 'X-N8N-API-KEY': 'ey*********' },
  body: formData
})
  .then(response => response.json())
  .then(data => console.log(data));

File Upload

// File Upload mode
const formData = new FormData();
formData.append('model', 'gpt-4o-mini');
formData.append('prompt', '...');
formData.append('content', '');
formData.append('llmKey', 'sk-proj-ERa23*******');
formData.append('file', fileInput.files[0]); // File object from <input type="file">

fetch('https://n8n.lchatai.com/execute/invoice-analytics', {
  method: 'POST',
  headers: { 'X-N8N-API-KEY': 'ey*********' },
  body: formData
})
  .then(response => response.json())
  .then(data => console.log(data));

Python

Text Content

import requests

url = "https://n8n.lchatai.com/execute/invoice-analytics"
headers = { "X-N8N-API-KEY": "ey*********" }

# Text Content mode
data = {
    "model": "gpt-4o-mini",
    "prompt": "...",
    "content": "Invoice text content here...",
    "llmKey": "sk-proj-ERa23*******",
    "file": ""
}
response = requests.post(url, headers=headers, data=data)
print(response.json())

File Upload

import requests

url = "https://n8n.lchatai.com/execute/invoice-analytics"
headers = { "X-N8N-API-KEY": "ey*********" }

# File Upload mode
data = {
    "model": "gpt-4o-mini",
    "prompt": "...",
    "content": "",
    "llmKey": "sk-proj-ERa23*******"
}
files = { "file": open("/path/to/invoice.pdf", "rb") }
response = requests.post(url, headers=headers, data=data, files=files)
print(response.json())

Php

Text Content

<?php
// Text Content mode
$url = "https://n8n.lchatai.com/execute/invoice-analytics";
$headers = ["X-N8N-API-KEY: ey*********"];
$data = [
    "model"   => "gpt-4o-mini",
    "prompt"  => "...",
    "content" => "Invoice text content here...",
    "llmKey"  => "sk-proj-ERa23*******",
    "file"    => ""
];
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
echo curl_exec($ch);
curl_close($ch);
?>

File Upload

<?php
// File Upload mode
$url = "https://n8n.lchatai.com/execute/invoice-analytics";
$headers = ["X-N8N-API-KEY: ey*********"];
$data = [
    "model"   => "gpt-4o-mini",
    "prompt"  => "...",
    "content" => "",
    "llmKey"  => "sk-proj-ERa23*******",
    "file"    => new CURLFile("/path/to/invoice.pdf")
];
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
echo curl_exec($ch);
curl_close($ch);
?>

Response

The response body contains the following two keys:

• response (string): The result of the invoice analysis, which provides the evaluation and rating of the submitted invoice.
• execution_id (integer): A unique identifier for the specific execution of the invoice analytics workflow.

{
  "response": ".....",
  "execution_id": 778
}