KSeF InvoSync

About

KSeF InvoSync is a free, open-source browser extension that connects the Polish National e-Invoice System (KSeF) to Google Sheets — automatically.

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✨ WHAT IT DOES
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▸ Pulls your invoices (outgoing + incoming) from KSeF every 30 min / 1h / 3h / 6h in the background
▸ Appends them to your own Google Sheet (two tabs: Invoices + Incoming)
▸ Shows a Dashboard tab with live formulas — totals, VAT, balance
▸ Adds 5 charts: gross by date, VAT trend, by buyer, monthly net
▸ Shows recent incoming invoices in a messenger-style feed with unread badges
▸ Click any incoming invoice to view it inline — FA(3) XML parsed on the fly (seller, buyer, line items, totals, due-date banner)
▸ One-click "Add to Calendar" on unpaid invoices — payment due date goes straight to Google Calendar with 3-day + 1-day popup reminders
▸ Download the original FA(3) XML for any invoice
▸ Chrome notifications for new invoices, sync results, errors

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🔒 SECURITY FIRST
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▸ Your KSeF token is encrypted with PBKDF2 + AES-256-GCM, protected by YOUR passphrase
▸ No backend server — data goes directly between your browser, KSeF, and Google
▸ No telemetry, no analytics, no tracking
▸ Uses browser-native Web Crypto API (SubtleCrypto) only — no third-party crypto libraries
▸ Minimal permissions: storage, alarms, notifications, identity (for OAuth)
▸ Open source under GPL-3.0 — verify every claim in the code

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⚡ FEATURES
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▸ Auto-extract NIP from pasted KSeF token — no manual typing
▸ Connection test button — verify your token works before syncing
▸ Sheet picker — choose an existing spreadsheet or create a new one
▸ Dedup — only NEW invoices are ever appended, no duplicates
▸ KSeF environment switch: Test / Demo / Production
▸ Full Polish + English interface (with manual language override)
▸ Dark/light mode (follows system or manual toggle)
▸ Status badge on the extension icon shows sync health at a glance
▸ "Remember passphrase" option — auto-sync survives browser restart

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🎯 WHO IT'S FOR
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▸ Polish SMBs (małe i średnie przedsiębiorstwa) who need KSeF compliance
▸ Accountants managing multiple invoice streams
▸ Freelancers who want their invoices backed up outside the KSeF portal
▸ Anyone who prefers Google Sheets over proprietary accounting software
▸ Developers who want to build on their invoice data (Sheets → custom analysis)

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📦 HOW IT WORKS
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1. Install the extension
2. Click the icon → Config tab → paste your KSeF token (NIP auto-detected) → set a passphrase → Set up vault
3. Connect your Google account → authorize Sheets + Drive access
4. Status tab → Sync now → your invoices appear in a new Google Sheet
5. Enable auto-sync → the extension keeps your sheet up-to-date automatically

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❓ REQUIREMENTS
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▸ A KSeF account (free, register at ap-test.ksef.mf.gov.pl or ap.ksef.mf.gov.pl)
▸ A KSeF token (generate from the KSeF web app)
▸ A Google account (for Sheets access)
▸ Chrome 120+ (or any Chromium-based browser)

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🔗 LINKS
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▸ Source code: https://github.com/k0ss11dev/KSeF-InvoSync
▸ Privacy policy: https://github.com/k0ss11dev/KSeF-InvoSync/blob/main/PRIVACY.md
▸ Issues / feedback: https://github.com/k0ss11dev/KSeF-InvoSync/issues
▸ License: GPL-3.0-or-later