Choose a repeatable numbering format
Set a prefix such as INV-2026-, a starting number and digit width. A three-digit width produces 001, 002 and 003. The tool previews and copies a batch; it does not reserve numbers or inspect your existing invoices.
Check before issuing
Compare each number with your issued-invoice register, including records from other devices. Do not silently reuse a number from an invoice already sent. Local storage is not a shared sequence for a team.