> ## Documentation Index
> Fetch the complete documentation index at: https://docs.chift.eu/llms.txt
> Use this file to discover all available pages before exploring further.

# Invoice

### Definition

In the Invoicing API, an invoice is a document that records a commercial transaction between a seller and a buyer. It states what was sold, the quantities, the prices, the applicable taxes, and the total amount due.

<Note>
  "Invoice" also exists in the [Accounting API](/unified-apis/accounting/concepts/invoice/index) (an entry that generates journal entries automatically) and the [PMS API](/unified-apis/pms/concepts/invoice) (a guest bill).
</Note>

### Purpose

Invoices drive the billing and collection cycle. They serve as the legal record of a sale or purchase.

### Relationships

* Each invoice belongs to a contact (customer or supplier).
* Each invoice line references a product and a tax rate.

### Endpoints

#### Read

| Method | Endpoint                                                                          | Description                    |
| ------ | --------------------------------------------------------------------------------- | ------------------------------ |
| GET    | [Retrieve all invoices](/api-reference/endpoints/invoicing/retrieve-all-invoices) | Returns a list of all invoices |
| GET    | [Retrieve one invoice](/api-reference/endpoints/invoicing/retrieve-one-invoice)   | Returns a single invoice by ID |

#### Write

| Method | Endpoint                                                                            | Description                                |
| ------ | ----------------------------------------------------------------------------------- | ------------------------------------------ |
| POST   | [Create an invoice](/api-reference/endpoints/invoicing/create-an-invoice)           | Creates a new invoice                      |
| POST   | [Upload a document (PDF)](/api-reference/endpoints/invoicing/upload-a-document-pdf) | Upload a PDF document linked to an invoice |

### See also

* [Contacts](/unified-apis/invoicing/concepts/contact)
* [Products](/unified-apis/invoicing/concepts/product)
* [Taxes](/unified-apis/invoicing/concepts/tax)