NASIP INVOICE STUDIO — BASIC PIN PRIVACY EDITION
25 October 2026

DESKTOP: Open Nasip-Invoice-Offline.html in a current Safari, Chrome, Edge or Firefox browser. It includes its code, layout and logo and needs no internet. Browser encryption support is required. Choose your PIN yourself; do not send it in a chat.

IPHONE/IPAD: Open https://nasipdoner.com/invoice/ in Safari while online. Set the PIN, enable offline, reopen the page once online, then Share > Add to Home Screen. Apple Files Quick Look may not execute downloaded HTML apps. ANDROID: use Chrome, enable offline and Add to Home screen / Install. Local HTML support depends on the chosen browser/viewer.

CUSTOMERS: Enter a customer name/address and press Save customer. Next time, type two or more letters in the customer name to see suggestions; choose one to fill the billing address, email and VAT number. Update existing entries with Save changes, or remove them from the list. Use Back up customers for an encrypted portable copy. Restore merges by name and address, replacing matches with backup details. Customer lists stay in this browser, encrypted with the current PIN. Changing the device PIN re-encrypts the local list automatically. Existing downloaded backups still need their original PIN. Clearing browser data removes the local list; restore your encrypted backup to recover it. No cloud sync.

PIN: Four digits provide BASIC PRIVACY ONLY, not secure online account authentication. The public app remains accessible to anyone. Each browser/device has its own lock; copies do not sync. PINs are never sent to a server. Only an encrypted verification value is saved in local browser storage, if available. Auto-lock occurs after five minutes without activity; Lock now is also available. A person with device/developer access can bypass a browser-only lock.

CHANGE PIN: Unlock, press Change PIN, enter the old PIN, new PIN and confirmation. Existing encrypted files ALWAYS keep the PIN used at save time. To convert a file: open it with its original PIN, then Save encrypted copy using the current device PIN. Keep the old PIN until all needed files are converted. No recovery is available if you forget a file PIN.

FILES: Save encrypted copy creates a .nasip.json file using AES-256-GCM, a random salt/nonce and PBKDF2-SHA256 (600,000 iterations). A four-digit PIN can still be guessed offline; this is not high-security protection for sensitive financial information. Save the encrypted file before closing; invoices are not automatically saved or synchronised. Older plain JSON files can be opened and saved as encrypted copies. The old plain file remains unencrypted until you separately remove it.

EMAIL: Customer email is saved with Save customer and fills again from suggestions. Complete the invoice, then press Email customer to review a message with invoice details. Open email app launches your default mail app; you choose the Nasip sender account and press Send yourself. Nothing is sent by the website. Save the PDF and attach it manually if wanted; encrypted JSON backups are not PDF attachments. For long messages, use Copy email text and paste into your mail app. Email preparation works offline but sending requires an internet connection and a configured mail account.

PDF: Print / save PDF uses your device print dialog. PDFs and paper printouts are NOT PIN-encrypted by this tool. Store them privately or use separate PDF encryption software. On iPhone/iPad, open print preview then Share > Save to Files.

RECOVERY: Clearing site browser data resets the device lock and can remove offline availability. It never decrypts existing files. Website backups contain the blank tool, not your chosen PIN or your invoices. Keep your PIN separately in a password manager and invoice backups in a private location.

BUSINESS: Confirm product prices, VAT status/registration/rates, payment instructions and unique invoice numbers before issuing. Nothing is prepriced. Nasip VAT number GB776822586 was verified against HMRC on 25 October 2026 and is prefilled for new invoices. VAT rates remain your choice; no rate is assumed. This is not an accounting ledger, payment service or filing integration.

COMPATIBILITY: Built for current desktop/mobile browsers. Chromium browser checks and cryptographic round-trip/wrong-PIN/tampering tests performed. Physical iOS, Android, Windows and Safari device tests remain outstanding.
