1. Do you really need paid KSeF software?

KSeF (Krajowy System e-Faktur) is Poland's national platform for issuing and receiving structured XML invoices. Access to KSeF itself is free — provided by the Ministry of Finance. What can cost money are the programs that add their own interface, integrations and automation on top.

For many companies — especially micro and small ones — the free tools are plenty. Below we show when that's the case, and when it's worth reaching for something more (also for free).

Need the legal context — deadlines, the 10,000 PLN exemption, penalties and error codes? We covered it separately: KSeF in 2026: timeline and practical preparation ↗.

2. Free government tools

The Ministry of Finance provides several free ways to issue KSeF invoices — with no licence fee:

  • Aplikacja Podatnika KSeF — the official free app (web and mobile) for issuing, receiving and viewing invoices. Log in via Profil Zaufany, among others. Good to start with and for a low document volume.
  • e-mikrofirma (inside e-Urząd Skarbowy) — a free tool aimed at the smallest firms, tied to settlements and records.
  • KSeF API — a free integration interface if you want to connect KSeF to your own system. It's not a "program" in itself, but a gateway to automation.

If you issue a handful to a dozen invoices a month and don't need integration with a warehouse or accounting — the government app will most likely be enough, and you'll pay nothing.

3. Where free government tools end

The MF tools are great to start, but they have limits. They start to hurt when:

  • you issue many invoices and manual entry eats real time;
  • you need invoices based on orders, warehouse, contracts or e-commerce — not "from scratch";
  • you handle corrections, prepayments and statuses in bulk, not one by one;
  • you want an invoice created automatically after an event in your system;
  • you need your own approval flows, roles and reporting.

That's usually when the "invoicing program" question appears. And it's worth knowing that the alternative to paid packages isn't only the government app — there are also free open-source solutions that combine the convenience of a program with a zero licence fee.

4. Open-source options: free, but with integration

Open-source software can be used without licence fees — on your own or with a partner. For KSeF we care about solutions that can:

  • generate a structured invoice and send it to KSeF;
  • receive confirmations and track statuses and errors;
  • connect invoices with the rest of the company — sales, warehouse, accounting;
  • grow with the company, without swapping systems every year.

These are built today on declarative low-code platforms (e.g. the lsFusion class), where logic is described by rules and the technical KSeF integration is hidden in connectors — so adapting to MF schema changes takes hours, not weeks.

A few real open-source options — with pros and cons (optional, no strings attached):
  • MyCompany — a free open-source ERP (Apache-2.0) on the lsFusion platform.
    Pro: it's a full ERP — invoices linked to sales, warehouse and accounting, process automation; the public demo includes invoice issuing. Con: as a platform it usually needs configuration for your processes (yourself or with a partner) — a higher entry bar than a simple invoicing app.
  • Dolibarr — a mature open-source ERP/CRM with a large community.
    Pro: plenty of ready modules, proven in thousands of firms. Con: a dated interface in places; Polish KSeF support is usually via third-party modules, not out of the box.
  • Invoice Ninja — a lightweight open-source invoicing app.
    Pro: simple and fast to start, focused on invoices and payments. Con: not a full ERP — no deep warehouse/production integration; no KSeF-specific features.

KSeF support varies between tools — worth checking each one. These are just examples; the choice depends on your company's scale and processes.

5. How to choose — a short checklist

  • Few invoices, simple? → the free Aplikacja Podatnika KSeF.
  • Smallest firm, tied to settlements? → e-mikrofirma.
  • Many invoices, warehouse/ERP integration, automation? → a program (paid or open-source).
  • Want to avoid a licence fee but still integrate? → open-source solutions.
  • Have your own system? → integrate via KSeF API.

6. Summary

"Free KSeF invoicing software" is no myth. Many companies will be fine with the free government tools, and where integration and automation are needed — open-source helps without licence fees. Before signing up for a paid module, check whether the free path already solves it at your scale.