File Uploads

When creating invoices or credit notes via the Billabex API, you need to attach a document file (PDF or image). This guide explains the supported file formats, size limits, and encoding options.

Overview

File uploads are required for:

• POST /api/public/v1/invoices – Create an invoice
• POST /api/public/v1/credit-notes – Create a credit note

Both endpoints accept multipart/form-data requests with a file attachment.

Supported File Formats

Size Limits

• Maximum file size: 10MB (decoded binary size)
• Files exceeding this limit will be rejected with a 400 Bad Request error

Encoding Options

Billabex supports two encoding methods for file uploads:

Binary Upload (Default)

Most HTTP clients send files as binary data by default. This is the recommended method when your platform supports it.

JavaScript Example

const formData = new FormData();
formData.append('accountId', 'ACCOUNT_ID');
formData.append('number', 'INV-2024-001');
formData.append('issuedDate.year', '2024');
formData.append('issuedDate.month', '1');
formData.append('issuedDate.day', '15');
formData.append('dueDate.year', '2024');
formData.append('dueDate.month', '2');
formData.append('dueDate.day', '15');
formData.append('totalAmount', '1500.00');
formData.append('taxAmount', '300.00');
formData.append('paidAmount', '0');
formData.append('billingAddress.street', '123 Main Street');
formData.append('billingAddress.city', 'Paris');
formData.append('billingAddress.postalCode', '75001');
formData.append('billingAddress.country', 'FR');
formData.append('file', fileBlob, 'invoice.pdf');

const response = await fetch('[baseURL]/api/public/v1/invoices', {
  method: 'POST',
  headers: {
    Authorization: `Bearer ${accessToken}`,
  },
  body: formData,
});

cURL Example

curl -X POST "[baseURL]/api/public/v1/invoices" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -F "accountId=ACCOUNT_ID" \
  -F "number=INV-2024-001" \
  -F "issuedDate.year=2024" \
  -F "issuedDate.month=1" \
  -F "issuedDate.day=15" \
  -F "dueDate.year=2024" \
  -F "dueDate.month=2" \
  -F "dueDate.day=15" \
  -F "totalAmount=1500.00" \
  -F "taxAmount=300.00" \
  -F "paidAmount=0" \
  -F "billingAddress.street=123 Main Street" \
  -F "billingAddress.city=Paris" \
  -F "billingAddress.postalCode=75001" \
  -F "billingAddress.country=FR" \
  -F "file=@invoice.pdf"

Base64 Upload

Some platforms (like NetSuite) cannot send binary data directly and must encode files as base64. Billabex automatically detects and decodes base64-encoded files.

To use base64 encoding:

1. Encode your file content as base64
2. Set the Content-Transfer-Encoding header to base64 in the file part

How Base64 Works

Base64 encoding converts binary data to ASCII text, increasing the size by approximately 33%. A 10MB file becomes ~13.3MB when base64-encoded.

Billabex handles this automatically:

• The 10MB limit applies to the decoded binary size
• Base64-encoded uploads up to ~13.7MB are accepted
• The file is decoded server-side before storage

JavaScript Example (Base64)

// Read file and encode as base64
const fileBuffer = await file.arrayBuffer();
const base64Content = btoa(String.fromCharCode(...new Uint8Array(fileBuffer)));

// Create multipart request with base64-encoded file
const boundary = '----WebKitFormBoundary' + Math.random().toString(36).slice(2);

const body = [
  `--${boundary}`,
  'Content-Disposition: form-data; name="accountId"',
  '',
  'ACCOUNT_ID',
  `--${boundary}`,
  'Content-Disposition: form-data; name="number"',
  '',
  'INV-2024-001',
  // ... other fields ...
  `--${boundary}`,
  'Content-Disposition: form-data; name="file"; filename="invoice.pdf"',
  'Content-Type: application/pdf',
  'Content-Transfer-Encoding: base64',
  '',
  base64Content,
  `--${boundary}--`,
].join('\r\n');

const response = await fetch('[baseURL]/api/public/v1/invoices', {
  method: 'POST',
  headers: {
    Authorization: `Bearer ${accessToken}`,
    'Content-Type': `multipart/form-data; boundary=${boundary}`,
  },
  body: body,
});

Node.js Example (Base64)

const fs = require('fs');
const path = require('path');

// Read file and encode as base64
const filePath = './invoice.pdf';
const fileContent = fs.readFileSync(filePath);
const base64Content = fileContent.toString('base64');
const filename = path.basename(filePath);

// Build multipart body manually
const boundary = '----FormBoundary' + Date.now();
const CRLF = '\r\n';

const parts = [`--${boundary}`, 'Content-Disposition: form-data; name="accountId"', '', 'ACCOUNT_ID', `--${boundary}`, 'Content-Disposition: form-data; name="number"', '', 'INV-2024-001', `--${boundary}`, 'Content-Disposition: form-data; name="issuedDate.year"', '', '2024', `--${boundary}`, 'Content-Disposition: form-data; name="issuedDate.month"', '', '1', `--${boundary}`, 'Content-Disposition: form-data; name="issuedDate.day"', '', '15', `--${boundary}`, 'Content-Disposition: form-data; name="dueDate.year"', '', '2024', `--${boundary}`, 'Content-Disposition: form-data; name="dueDate.month"', '', '2', `--${boundary}`, 'Content-Disposition: form-data; name="dueDate.day"', '', '15', `--${boundary}`, 'Content-Disposition: form-data; name="totalAmount"', '', '1500.00', `--${boundary}`, 'Content-Disposition: form-data; name="taxAmount"', '', '300.00', `--${boundary}`, 'Content-Disposition: form-data; name="paidAmount"', '', '0', `--${boundary}`, 'Content-Disposition: form-data; name="billingAddress.street"', '', '123 Main Street', `--${boundary}`, 'Content-Disposition: form-data; name="billingAddress.city"', '', 'Paris', `--${boundary}`, 'Content-Disposition: form-data; name="billingAddress.postalCode"', '', '75001', `--${boundary}`, 'Content-Disposition: form-data; name="billingAddress.country"', '', 'FR', `--${boundary}`, `Content-Disposition: form-data; name="file"; filename="${filename}"`, 'Content-Type: application/pdf', 'Content-Transfer-Encoding: base64', '', base64Content, `--${boundary}--`];

const body = parts.join(CRLF);

const response = await fetch('[baseURL]/api/public/v1/invoices', {
  method: 'POST',
  headers: {
    Authorization: `Bearer ${accessToken}`,
    'Content-Type': `multipart/form-data; boundary=${boundary}`,
  },
  body: body,
});

Python Example (Base64)

import base64
import requests

# Read and encode file
with open('invoice.pdf', 'rb') as f:
    file_content = f.read()
    base64_content = base64.b64encode(file_content).decode('ascii')

# Build multipart body
boundary = '----PythonFormBoundary'
crlf = '\r\n'

body_parts = [
    f'--{boundary}',
    'Content-Disposition: form-data; name="accountId"',
    '',
    'ACCOUNT_ID',
    f'--{boundary}',
    'Content-Disposition: form-data; name="number"',
    '',
    'INV-2024-001',
    # ... other fields ...
    f'--{boundary}',
    'Content-Disposition: form-data; name="file"; filename="invoice.pdf"',
    'Content-Type: application/pdf',
    'Content-Transfer-Encoding: base64',
    '',
    base64_content,
    f'--{boundary}--',
]

body = crlf.join(body_parts)

response = requests.post(
    '[baseURL]/api/public/v1/invoices',
    headers={
        'Authorization': f'Bearer {access_token}',
        'Content-Type': f'multipart/form-data; boundary={boundary}',
    },
    data=body.encode('utf-8'),
)

Error Handling

Example error response:

{
  "statusCode": 400,
  "message": "File too large. Maximum size: 10485760 bytes",
  "error": "Bad Request"
}

Best Practices

Choose the Right Encoding

• Use binary (default) whenever possible – it’s more efficient
• Use base64 only when your platform doesn’t support binary uploads

Validate Files Client-Side

Check file size and type before uploading to avoid unnecessary API calls:

const MAX_SIZE = 10 * 1024 * 1024; // 10MB
const ALLOWED_TYPES = ['application/pdf', 'image/png', 'image/jpeg', 'image/webp'];

if (file.size > MAX_SIZE) {
  throw new Error('File too large');
}

if (!ALLOWED_TYPES.includes(file.type)) {
  throw new Error('Invalid file type');
}

Use PDF When Possible

PDF is the recommended format for invoice documents:

• Preserves formatting across devices
• Supports text extraction
• Smaller file sizes for text-heavy documents

Next Steps

• Getting Started – API basics and authentication
• API Reference – Full endpoint documentation

Support

Questions about file uploads?
Contact us via the website contact form.