Pick a numbering format, set a prefix, start number and padding, and copy your next invoice numbers. Sequential, year, date or per-client. No signup.
Do this automatically
Save your clients, email each invoice with the PDF attached and see what is paid, due or overdue. Clients pay from the invoice email without creating an account. The Free plan covers 5 invoices a month.
Free plan · no credit card · cancel anytime
Any consistent, sequential, non-repeating scheme works. Popular ones: simple sequential (INV-1001), year-based (INV-2026-0001), date-based (202606-0001) or per-client (ACME-0014). Pick one and never change it mid-year.
No — starting at 1001 avoids telling every client "you are my first customer." It is a harmless bit of presentation.
Unique, sequential numbers keep your bookkeeping auditable and are legally required in many places. Never reuse a number, even for a cancelled invoice — void it and move on.
Yes — BillingOtter assigns the next number automatically in your chosen format, forever, with no repeats. This tool is the manual version.