Need intuitive and functional business software? Then learn more about the software offered by the third-party provider KSeF API. It's a good alternative to the official National e-Invoice System. What can you gain by using ready-made libraries, comprehensive documentation, and integration via XML and XSD files? Learn more and discover what makes KSeF API unique!
What exactly is KSeF API and why is it development software?
KSeF API is a set of ready-made mechanisms (REST API and libraries in PHP, Java, .NET) for generating, sending and downloading e-invoices in XML format in accordance with the requirements of the National e-Invoice System.
It enables quick creation of invoices, sending with UPO, PDF/HTML visualization and document search. This software is evolving because it deftly handles complex integration, certificates, cryptography, and invoice schema changes. It also supports the 2.0 model (OpenAPI, SDK, testing, production), ensuring up-to-date, stable, and easily maintainable implementations.
KSeF is Poland's National E-Invoice System, developed by the Ministry of Finance. Its goal is to standardize the issuing, receiving, and storing of electronic commercial documents in a structured format.
In practice, thanks to KSeF, entrepreneurs:
- issue invoices in a standardized format;
- they send electronic documentation via the online system without generating e-mails and PDF files;
- have access to commercial documentation for 10 years from the date of invoice issuance.
A major advantage of the system is that there's no requirement to store paper documents. If you run a business, you should prepare, as the system will likely become mandatory for most businesses in the country starting in 2026.
KSeF API's greatest achievements
The commercial KSeF API from kssefapi.pl simplifies integration with the National e-Invoice System and shortens implementation time. It helps companies more quickly comply with new legal obligations.
What has already been achieved with KSeF API?
- the technical process of implementing KSeF in hundreds of companies has been simplified;
- the time needed for integration was reduced by up to several dozen hours;
- ready-made libraries for PHP, .NET and Java are available;
- better documentation was provided than in the official API of the Ministry of Finance;
- enabling the creation of e-invoices via web and mobile applications;
- complicated technical aspects such as X.509 and PKI certificates are bypassed.
This solution allows entrepreneurs to focus on running their business, rather than on the technical complexities of issuing invoices. Integration with KSeF can be quick, simple, and predictable, simply by leveraging the KSeF API integration.
What are the KSeF API integration options? Comprehensive technical support
Ksefapi.pl offers ready-made libraries, an intuitive REST API, and documentation that actually answers your questions. You can count on support not only after implementation, but from the very first contact.
There are two integration options to choose from, namely:
- Do-it-yourself integration, which involves a significant amount of work and time spent understanding the KSeF system's operating principles, generates higher initial costs, while subsequent system maintenance is somewhat less expensive.
- Integration using ksefapi.pl – in this case, you gain the opportunity to carry out a quick and easy implementation with costs distributed evenly throughout the entire period of cooperation.
You can also choose from a variety of licensing options to suit the needs and characteristics of your business.
Whenever necessary, you report a problem and immediately know that someone on the other end is actually looking into it. The team not only refers you to documentation, but also reviews logs and code, and creates ready-made fixes. You communicate directly with a specific person – you have their number, you can call them, and together, solve the problem.
You can also be sure that the system will be updated in line with changes in KSeF. And if you submit a suggestion, it may become a new feature.
What makes KSeF API stand out from other interfaces?
The advanced KSeF API system stands out primarily for its functionality, which is constantly being expanded with new modules. The basic features available after integrating the API with the National e-Invoice System, which distinguish our system, include:
- sending and receiving invoices and UPOs directly from the KSeF system;
- generating invoices in a unified XML format;
- access to previews in PDF format;
- support for bulk sending of e-invoices.
Another advantage is automatic notifications when a new e-invoice is received. This means you don't have to worry about missing any payments, such as those for goods.
A unique offer with a wide range of KSeF API licenses – what is worth knowing?
KSeF API offers flexible licensing tailored to your business. You can choose a billing model based on the number of transactions, invoices, or customers. You only pay for what you actually need.
As part of KSeF API integration:
- You can use the KSeF API for free until February 1, 2026.
- In the operations license, you only pay for queries made to the REST system.
- In the "invoice-based" model, you only handle sales – cost invoices are unlimited.
- In the "customer" package, there is no limit on operations or invoices - only the number of supported Tax Identification Numbers counts.
- Individual versions provide access to features such as a local container or e-invoice queue.
- Each plan includes data encryption and technical support – via email or telephone.
By choosing one of our implementation plans, you gain real control over your company's costs. You can tailor the integration method to the scale of your business, all with the goal of further standardizing the way your company stores business records.
Unique KSeF API offer – access to know-how and diverse licenses
Ksefapi.pl's strength lies in its extensive experience. The team specializes in creating APIs and various integrations that simplify enterprise management. Over 20 years of experience, high qualifications, and implementations that have been tested with hundreds of clients.
The specific nature of the KSeF system is truly challenging, especially when it comes to complex implementations. Our team addresses these challenges and offers flexible licensing tailored to your company's needs.
Integration with KSeF? Find out why ksefapi.pl is the best solution!
