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KSeF Connector

Do you want to handle invoices in your company even more conveniently? Choose KSeF Connector – a web service that will connect your software with the National e-Invoicing System (KSeF) and facilitate your daily work.

Free consultation

What is KSeF?

The National e-Invoicing System (KSeF) is an IT system provided by the Ministry of Finance for sending and receiving invoices in a structured form (XML). The system was created to collect, analyze, and control data from issued invoices. The head of the National Tax Administration is the administrator of the collected data.

The system’s production launch took place on January 1, 2022. However, at present, structured invoices operate in the economic circulation as one of the permissible forms of documenting transactions, alongside paper and electronic invoices. Currently, the date from which sending invoices to KSeF will be mandatory is unknown (the expected date is mid-2024).

KSeF Connector

KSeF Connector is a web service that connects the client’s software with the National e-Invoicing System (KSeF). The system consists of two modules: one for sending sales invoices and another for receiving purchase invoices. With an endpoint installed at the client’s location, KSeF Connector enables integration with any ERP system. The software is available in two variants:

  • As an automatic data exchange service – completely automated and operates without user intervention (no dedicated interface). Data is retrieved from the ERP system, processed, validated for accuracy, and sent to the National e-Invoicing System. The response from KSeF is also automatically retrieved and forwarded to the ERP system.
  • As a document repository functionality – in this version, the solution includes all functionalities described in point 1 and provides a user interface, allowing employees to view sent and received invoices directly in the KSeF Connector system.

Benefits of using KSeF Connector

This solution provides, among others:


Integration of multiple ERP systems for multiple companies

Support for attachments

A module for monitoring system availability

Additional validation before sending the document to KSeF

Functionalities of KSeF Connector

  • Ability to integrate with any ERP system
  • Download and upload history, statuses, invoice numbers, and UPOs
  • Support for multiple companies
  • Maximum automation
  • Support from the analysis process through implementation to operational support
  • Field mapper from the client’s format to the KSeF format
  • Error notifications in transmitted invoices
  • Automatic monitoring of system availability
  • Technical validations – ensuring compliance with the KSeF format before sending to the Ministry of Finance’s KSeF
  • Sending sales invoices with status handling and feedback
  • Duplicate invoice detection
  • Email notifications about new invoices
  • Processing and workflow of invoices directly in KSeF Connector
  • Receiving purchase invoices
  • Visualization of sales and cost invoices
  • Business validations (up to three individual validations)
  • Ability to assign invoices to specific people based on invoice parameters (e.g., contractor’s NIP)
  • Integration module with any ERP workflow system
  • Manual (on-demand) and automatic retrieval of cost e-invoices from KSeF
  • Forwarding retrieved e-invoices to related systems (ERP, workflow)
  • Manual (on-demand) and automatic retrieval and sending of sales e-invoices
  • Feedback from KSeF with ksefRefNumber, invoice date, and UPO
  • Processing and workflow of invoices directly in KSeF Connector
  • Visualization of sales and cost invoices
  • Mechanism for checking the availability of all systems involved in the process
  • Error notifications in transmitted invoices
  • Management of access rights to invoices
  • Invoice reports and summaries

How KSeF Connector WORKS

KSeF Connector is available in two variants:

  • As a cloud service
  • As an application installed on the client’s environment

The diagram next to this text visualizes the process of sending and receiving invoices.

Communication Methods and data exchange formats

Depending on the client’s specific needs, KSeF Connector supports the following communication channels:

  • WebService SOAP and REST API
  • Database view
  • Files shared on a disk
  • File import


KSeF Connector supports the following data formats:

  • XML
  • JSON
  • Excel files
  • Text files in a specified format

What does the implementation of KSeF Connector look like?

Pre-implementation analysis

At the very beginning of the implementation, a technical analysis will be conducted, consisting of three stages.

Stage 1: refining technical and business requirements

We will discuss and document your requirements and propose effective solutions. This stage will cover all validations, attachment handling, invoice sending, and document workflow.

Stage 2: integration with other systems

We will work together to determine the best integration method (available channels include WebService SOAP and REST API, database view, files shared on a disk, file import) and agree on the formats of the data being transferred (XML, JSON, Excel files, text files in a specified format). Additionally, we will plan the feedback communication with KSeF, establishing communication channels and the location for delivering information (sending status, invoice receipt date, KSeF number, and UPO).

Stage 3: mapping fields from the client’s format to the KSeF format

During this stage, we will analyze the data provided by the financial and accounting system and propose a mapping of source data to the KSeF format.

The result of these three steps will be a pre-implementation analysis document approved by both parties.

  • Technical architecture development – we will develop a technical architecture diagram that includes the recommended hardware configuration for both production and test environments. Additionally, this stage will result in the solution sizing.
  • Installation and configuration of the application – a Cloud Agent will be installed in your environment, allowing external communication without needing firewall exceptions. We will then configure the KSeF Connector to enable sending and receiving invoices with KSeF.
  • Integration with client systems – based on the pre-implementation analysis, we will integrate the KSeF Connector with the client’s systems, including both financial-accounting and workflow systems.
  • Field mapping – the built-in mapper will be used to map fields from the source format to the KSeF format. Each source data point can be assigned to the appropriate field in the KSeF format, based on the approved analysis document.
  • Testing in the client’s environment – during the testing phase, we will connect the KSeF Connector to the Ministry of Finance’s KSeF demo environment, where all invoices will be sent. The demo environment has the full functionality of the production environment but without legal consequences for the invoices sent. This approach ensures safe configuration and field mapping verification.
  • Production launch – after testing, the application will go live, and documents will be sent to the production KSeF environment.
  • Final documentation – updated final documentation will be provided upon completion of the implementation.
  • Training – if requested, we will conduct training sessions for your team.
  • Post-implementation maintenance as part of application support.
  • Assurance of updates to the latest KSeF format as part of maintenance or subscription.

Schedule a free consultation

with one of our specialists. We will demonstrate step by step how to effectively optimize invoice workflow in your company using KSeF Connector.

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