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

# Fetch invoices

> Step-by-step guide to fetch invoices from multiple accounting systems using a single Unified API.

## Fetch invoices from other systems in 5 steps

<Steps>
  <Step title="Authorize access" titleSize="h3">
    Your user must first authorize your application to access their accounting platform (e.g., Xero, Lexware Office, Sevdesk) via an authorization flow (e.g., OAuth, API key) through [maesn Connect](/guides/maesn-connect).
  </Step>

  <Step title="Retrieve filtered list of invoices" titleSize="h3">
    Start by retrieving a list of invoices by calling GET [/invoices](/api-reference/accounting-endpoints/invoices/get-invoices) and applying the appropriate filters, for example invoice date, invoice status or payment status, to give your users an overview of their invoices.
  </Step>

  <Step title="Show invoice details" titleSize="h3">
    When the end user has selected a specific invoice, present all the details including line items by calling GET [/invoices/\{id}](/api-reference/accounting-endpoints/invoices/get-invoice).
  </Step>

  <Step title="Retrieve the invoice document (optional)" titleSize="h3">
    Present original PDF documents by calling GET [/invoices/\{id}/document](/api-reference/accounting-endpoints/invoices/get-invoice-document).
  </Step>

  <Step title="Retrieve captured invoices (optional)" titleSize="h3">
    In addition, to invoices originally created in the respective accounting platforms, invoices created elsewhere and subsequently uploaded to the accounting platform can be retreived through

    * GET [/bookingProposals](/api-reference/accounting-endpoints/bookingproposals/get-booking-proposals)
    * GET [/bookingProposals/\{id}](/api-reference/accounting-endpoints/bookingproposals/get-booking-proposal)
    * GET [/bookingProposals/\{id}/document](/api-reference/accounting-endpoints/bookingproposals/get-booking-proposal-document).
  </Step>
</Steps>

<Tip>You can utilize Webhooks to make this process more efficient.</Tip>