Good business.
Clearly invoiced.

Use your own unique invoice numbering sequence. Numbers are not reserved or checked across devices.

Prices are in GBP. With VAT enabled, enter prices excluding VAT. Product prices and VAT rates have not been supplied: enter the agreed values.

Payment details are not prefilled. Check them with the business before sharing an invoice.

Editable files are encrypted with your current device PIN. Printed PDFs are not encrypted. Saved customers are stored encrypted in this browser only. Nothing is sent automatically or saved to a server. Save an editable copy before closing. For a PDF, use your browser’s print options. On iPhone/iPad, open the print preview and use Share → Save to Files.

On iPhone/iPad: open this tool in Safari, enable offline, then Share → Add to Home Screen. On Android, use Chrome’s Add to Home screen / Install option. Open it online once before using it offline. Clearing browser data removes offline availability; keep exported invoice copies separately.