| List Vouchers | Read | List and filter bookkeeping vouchers (sales and purchase invoices, credit notes) via the voucherlist, e.g. to find open or overdue invoices |
| Get Invoice | Read | Retrieve a single invoice with line items, totals, tax conditions, and payment status |
| Create Invoice | Write | Create a sales invoice. Created as an editable draft by default; set finalize=true to immediately open it |
| List Contacts | Read | List and filter customers and vendors, e.g. to find the contactId for an invoice |
| Create Contact | Write | Create a customer or vendor contact for use on invoices and vouchers |
| Upload Voucher File | Write | Upload a receipt image or invoice file (pdf, jpg, png, xml; max 5 MB) for bookkeeping; returns the file id and the id of the voucher created for it |
| Download File | Read | Download an uploaded bookkeeping voucher file (receipt/invoice image) as binary data by its file id; Content-Type and Content-Disposition response headers carry the MIME type and suggested filename. For sales voucher documents prefer the document render flow. |
| Get Invoice Document | Read | Trigger PDF rendering for an invoice and return its documentFileId, which can then be downloaded via Download File. Required for invoices created through the API with status open; draft invoices have no document file and are rejected with 406. |
| Get Payments | Read | Get the payment status of an invoice or voucher: open amount, paid date, and payment items - the reliable way to check who actually paid |
