Unique Invoice Numbers Across Multiple Macs

The problem

You write invoice 2026-042 on your MacBook and send it. Before the sync reaches the iMac, the next invoice is created there — and gets 2026-042 as well. Rare, but unpleasant: invoice numbers must be unique by law, and the PDF is already with the recipient.

The solution

Just before assigning the number for good, GrandTotal asks a small reservation server hosted by Media Atelier whether it's still free. If not, it jumps to the next available number automatically. The request takes milliseconds — you won't notice.

What gets transmitted

Only the document identifier and the invoice number itself. No customer data, no amounts, no line items. Reserved numbers are deleted after a few days.

Document: 6b7a4e9c-2f31-4d8a-9b6e-0c1f2a3d4e5f
Type:     Invoice
Number:   2026-042

The document identifier is a random UUID.

Opt-in and fallback

The feature is off by default and can be enabled with the Check uniqueness online option in the settings under Invoices or Estimates — right where you also configure the number format. If the server is unreachable, GrandTotal falls back to local numbering — no blocking, no error.