Introduction

Fast KSeF is a web application designed for issuing, sending, and receiving structured invoices within the National e-Invoice System (KSeF).

Key Features

• 🔐 Secure Authentication — Sign in via Google, Microsoft, or Apple ID, using KSeF certificates.
• 📄 Invoice Creator — A step-by-step wizard: buyer details, line items, additional options, preview, and submission.
• 🔄 KSeF Synchronization — Fetch sales, purchase, and third-party invoices directly.
• 📑 Corrective Invoices — Create credit/debit notes linked to original source invoices.
• 🏢 Contractors — Search the GUS/BIR register and verify status on the VAT White List.
• 📦 Product Catalog — Predefined items with GTU codes and PKWiU classifications.
• 🔑 KSeF Session Management — Monitor active sessions and renew authorization tokens.
• ⚙️ Company Settings — Manage address details, Tax ID (NIP), bank account numbers, and invoice numbering patterns.

KSeF Environments

The application supports three KSeF environments:

Environment	Description	Use Case
Test	MF Test Environment	Training and testing
Demo	MF Demo Environment	Demonstrations
Production	MF Production Environment	Real invoices

Attention

Invoices sent to the Production environment have legal consequences. Use the Test environment for learning and testing.

Requirements

• Web browser (Chrome, Firefox, Edge, Safari)
• User account (registration via Google or Microsoft)
• KSeF certificate (test or production) for KSeF authorization

Getting Started

Go to the Getting Started section to create an account and configure the application.