Invoice Generator API

Custom fields allow you to add extra information to the top-right section of the invoice. These are passed as an array of objects containing name and value keys.

{
  "custom_fields": [
    {
      "name": "Gizmo",
      "value": "PO-1234"
    },
    {
      "name": "Account Number",
      "value": "CUST-456"
    }
  ]
}

To use the API, you must first obtain an API key:

1. Create a free account at Invoice-Generator.com.
2. Navigate to the Settings page.
3. In the API Keys section, click New API Key.

Note: The free plan is limited to 100 invoices per month. Higher limits require a paid subscription.

You can change the language of the invoice template by providing an Accept-Language header. The default is en-US.

Supported Languages:

• English
• French
• German
• Spanish
• Thai

curl https://invoice-generator.com \
  -H "Authorization: Bearer myApiKey" \
  -H "Accept-Language: fr-FR" \
  -d from="Nikolaus Ltd" \
  -d to="Acme Corp." \
  -d number=1 \
  -d currency=eur \
  -d "items[0][name]"="Starter plan monthly" \
  -d "items[0][quantity]"=1 \
  -d "items[0][unit_cost]"=99 \
> invoice.pdf

The primary endpoint returns a PDF invoice based on the provided details. You can send data via form-encoded parameters or as a JSON body with Content-Type: application/json.

Endpoint: POST https://invoice-generator.com
Authentication: Bearer Token via Authorization header.

curl https://invoice-generator.com \
  -H "Authorization: Bearer myApiKey" \
  -d from="Nikolaus Ltd" \
  -d to="Acme, Corp." \
  -d number=1 \
  -d "items[0][name]"="Starter plan monthly" \
  -d "items[0][quantity]"=1 \
  -d "items[0][unit_cost]"=99 \
> invoice.pdf

The API can generate e-invoices in UBL (Universal Business Language) XML format. This format includes the invoice PDF embedded within the XML. It uses the same parameters as the standard PDF endpoint.

Endpoint: POST https://invoice-generator.com/ubl

curl https://invoice-generator.com/ubl \
  -H "Authorization: Bearer myApiKey" \
  -d from="Nikolaus Ltd" \
  -d to="Foster Moen" \
  -d "items[0][name]"="Starter Plan Monthly" \
  -d "items[0][quantity]"=1 \
  -d "items[0][unit_cost]"=99 \
> invoice.xml

Line items are passed as an array of objects within the items parameter.

{
  "items": [
    {
      "name": "Gizmo",
      "quantity": 10,
      "unit_cost": 99.99,
      "description": "The best gizmos there are around."
    },
    {
      "name": "Gizmo v2",
      "quantity": 5,
      "unit_cost": 199.99
    }
  ]
}

The fields object toggles the visibility of discounts, tax, and shipping subtotal lines. Each setting can be % (for percentage-based tax), true, or false. Use the corresponding tax, discounts, or shipping keys to provide the numeric values.

{
  "fields": {
    "tax": "%",
    "discounts": false,
    "shipping": true
  },
  "tax": 7,
  "shipping": 15
}

These parameters control the labels/titles used in the invoice template. Providing a value overrides the localized default.

| Parameter | Default Value |
|:---|:---|
| `header` | INVOICE |
| `to_title` | Bill To |
| `ship_to_title` | Ship To |
| `invoice_number_title` | # |
| `date_title` | Date |
| `payment_terms_title` | Payment Terms |
| `due_date_title` | Due Date |
| `purchase_order_title` | Purchase Order |
| `quantity_header` | Quantity |
| `item_header` | Item |
| `unit_cost_header` | Rate |
| `amount_header` | Amount |
| `subtotal_title` | Subtotal |
| `discounts_title` | Discounts |
| `tax_title` | Tax |
| `shipping_title` | Shipping |
| `total_title` | Total |
| `amount_paid_title` | Amount Paid |
| `balance_title` | Balance |
| `terms_title` | Terms |
| `notes_title` | Notes |