Improved
Attachments API improvements
November 5th, 2025
In the attachments API endpoint, we have introduced the replaceInvoicePdf field. In the Upload invoice attachment (POST /v3/attachments/invoices/{invoiceId}) request, you can now set the replaceInvoicePdf field as true to replace the existing invoice PDF with a new PDF attachment.
The invoice PDF is sent as an email attachment when you send an invoice to a customer. The invoice PDF also appears when the customer clicks the invoice payment link to complete the invoice payment.
See POST /v3/attachments/invoices/{invoiceId} in the API reference for more information.