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KsefInvoice vs Rechnungs-Assistent: catalog facts
KsefInvoice	Rechnungs-Assistent
Free Freeware with no subscription or per-document KSeF fees.	Free Free and open source under the GPL-3.0-or-later license.
Windows, Linux	Linux
Sends and retrieves documents through KSeF Handles invoices, corrections, receipts and multiple currencies	Stores customer and item details for reuse Imports and exports data as CSV
Interface is currently available only in Polish Focused on Polish tax and e-invoicing systems	Designed for German invoicing Available for Linux
Downloadable app	Downloadable app
Closed source	Open source
License: Freeware	License: GPL-3.0-or-later
Not stated if an account is needed	Not stated if an account is needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked October 8, 2026	Official website Full listing and sources Checked October 8, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.