Short, task-by-task answers.
Open the app — it opens directly into a new, blank invoice. Fill in "Your business," add a client under "Bill to," add line items, then click "Save."
Check "Apply tax" to add a tax line with a custom label (VAT, GST, etc.); set a discount as a percent or flat amount; use "Duplicate" to start a new draft from an existing document; convert a saved estimate to an invoice with one click; delete a document with a confirmation step first.
Everything you enter is stored locally in this browser. Nothing is uploaded to a server. Export a backup from "Backup & Restore," and restore from a backup file the same way, with a warning before anything is replaced.
Export a backup on your current device, move the file yourself (email, USB drive, cloud storage), then import it on the new device or browser.
PDFs are generated at A4 size. "Download PDF" saves a file; "Share" opens your device's native share sheet where supported. To print, download the PDF and print it from your device's own PDF viewer.
After you've loaded the app once with a connection, it keeps working offline — creating, editing, and downloading PDFs all work with no internet connection.
Covers: finding an old invoice, a PDF that won't export, a failed restore, clearing browser data, international characters not displaying, using the app offline, and moving a backup file between devices.