# Generate invoice for shipment

Generate an invoice PDF for the shipment.

## What happens

- Invoice PDF is generated
- Invoice document is attached to the shipment
- Shipment billing status changes to INVOICED

## Prerequisites

- Shipment must be in READY_TO_INVOICE status

Endpoint: POST /shipments/{id}/invoice/generate
Version: 1.0.0
Security: BearerAuth

## Path parameters:

  - `id` (string, required)
    Resource ID (UUID) or client key
    Example: "550e8400-e29b-41d4-a716-446655440000"

## Query parameters:

  - `by` (string)
    Specify lookup type for faster retrieval.
If omitted, defaults to looking up by ID first, then falls back to client key if not found.
Use by=key when you know you're providing a client key for best performance.
    Enum: "id", "key"

## Response 200 fields (application/json):

  - `shipmentId` (string)

  - `invoiceId` (string)
    The generated invoice ID

  - `documentId` (string)
    The invoice PDF document ID

  - `downloadUrl` (string)
    URL to download the invoice PDF

## Response 400 fields (application/json):

  - `error` (string, required)
    Error code

  - `message` (string, required)
    Human-readable error message

## Response 401 fields (application/json):

  - `error` (string, required)
    Error code

  - `message` (string, required)
    Human-readable error message

## Response 404 fields (application/json):

  - `error` (string, required)
    Error code

  - `message` (string, required)
    Human-readable error message

## Response 409 fields (application/problem+json):

  - `error` (string, required)
    Error code

  - `message` (string, required)
    Human-readable error message