Invoicing with KSeF: 6 Tools Compared

Why This Comparison Exists

KSeF — Poland's National e-Invoice System — makes the choice of invoicing software consequential in a way it was not before. In the pre-KSeF world, switching tools was straightforward: export your data, sign up elsewhere, and continue. With KSeF, your software connects directly to the Ministry of Finance's API, and every invoice you issue carries a KSeF number that is part of a permanent, government-held record. Choosing a tool that handles this integration poorly — or that lacks features you need — is harder to undo.

This comparison reviews six tools available to Polish businesses in 2026. We have tried to be honest about each product's weaknesses, including our own. If you are primarily looking for free KSeF invoicing software, read our complete guide to free invoicing software with KSeF first, then return here for the deeper comparison.

What We Evaluated

Each tool was assessed on seven criteria:

1. KSeF integration quality — does it send and receive correctly, handle errors gracefully, and store KSeF numbers reliably?
2. Ease of use — how long does it take a non-accountant to issue a first invoice?
3. Price — true cost, including per-invoice fees where applicable
4. Accounting depth — is it invoicing-only, or does it include bookkeeping, VAT returns, and payroll?
5. Automation — recurring invoices, payment reminders, client portal
6. Mobile access — native app quality and offline capability
7. Support quality — response time, documentation depth, Polish-language support

The Six Tools

1. Terminovo

Best for: Small B2B businesses that want free KSeF invoicing tightly integrated with automated payment reminders.

Strengths: Terminovo's core proposition is the combination of KSeF-compliant invoicing and automated payment recovery in one workflow. When you issue an invoice, the reminder sequence can start automatically from the due date — no manual setup per invoice. The free plan covers KSeF invoicing without limits on invoice count. The interface is clean and fast for businesses issuing straightforward B2B invoices.

Weaknesses: Terminovo is a younger product. It does not include full accounting or VAT return preparation — you will still need an accountant or separate bookkeeping software. There is no native mobile app as of April 2026 (the web interface is mobile-responsive, but it is not an app). If your invoicing needs are complex — split-payment invoicing, extensive custom fields, multi-currency — you may find the feature set limited compared with older, larger platforms.

Price: Free plan for KSeF invoicing. Paid plans for advanced reminder sequences and analytics.

Verdict: A strong choice if payment recovery matters as much as invoicing to you. Weaker as a standalone accounting tool.

2. Fakturownia

Best for: Small to medium businesses wanting a mature, feature-rich invoicing platform with broad integration options.

Strengths: One of Poland's most established invoicing platforms. Excellent API and integration ecosystem — connects with most Polish accounting software, e-commerce platforms, and payment gateways. KSeF integration is mature and well-tested. Strong template customisation. Multi-currency support is solid. The mobile app is genuinely good.

Weaknesses: The pricing model charges per invoice above plan limits, which can become expensive for high-volume issuers. The interface has accrued complexity over the years — there is a lot of functionality, and finding specific settings takes time. Payment reminder automation is basic compared with dedicated tools.

Price: Plans from approximately PLN 19/month for basic, rising significantly for higher invoice volumes.

Verdict: The safe, proven choice for businesses that issue varied invoice types and need reliable integrations. Not ideal if cost per invoice is a concern at scale.

3. inFakt

Best for: Sole traders (JDG) and freelancers who want invoicing and basic bookkeeping in one place, with access to an online accountant.

Strengths: inFakt has built its brand around being genuinely easy for non-accountants. The onboarding is the smoothest of any tool on this list. KSeF integration works reliably. The optional access to inFakt's accountant network — where a licensed accountant handles your VAT returns and annual filings — is a real differentiator for sole traders who do not want to think about accounting at all.

Weaknesses: The accountant add-on is expensive (PLN 250–400/month) and is really the product's premium offering — without it, the feature set is narrower than Fakturownia or wFirma. Customisation of invoice templates is limited. Not well-suited to companies with multiple users or complex approval workflows.

Price: Free plan for basic invoicing; accounting add-on from ~PLN 250/month.

Verdict: Best for freelancers and sole traders who want to outsource their accounting. Overkill — or underpowered — for companies with internal finance teams.

4. wFirma

Best for: Growing SMEs that need full cloud accounting, not just invoicing.

Strengths: wFirma is the most accounting-complete product on this list. It handles KPiR (revenue and expense ledger for JDGs), full books for companies, VAT-7 and VAT-7K returns, payroll, ZUS declarations, and more — all in one platform. KSeF integration is solid. The pricing is reasonable given the breadth of functionality. Multi-user access with role-based permissions is well-implemented.

Weaknesses: The learning curve is steeper than inFakt or Fakturownia. The interface looks and feels like accounting software, which it is — if you want simplicity, this is not the tool. Mobile app is functional but not polished. Payment reminder functionality is rudimentary.

Price: From approximately PLN 49/month for sole traders, higher for companies and payroll users.

Verdict: The right tool if you need genuine cloud accounting. Not the right tool if you just need fast, simple invoicing.

5. iFirma

Best for: Cost-conscious sole traders and small companies wanting accounting plus invoicing at a flat, predictable price.

Strengths: iFirma has one of the most transparent pricing structures in the market — flat monthly fee, no per-invoice charges, no surprise tiers. Full accounting for JDGs and sp. z o.o. companies is included. KSeF integration is present and functional. The accountant-assistance model (where you manage the books but iFirma-affiliated accountants are available for questions) suits businesses that want to stay in control without being entirely on their own.

Weaknesses: The interface is dated. The product has not been redesigned significantly in several years, and it shows compared with newer tools. Mobile access is limited. Integration options with third-party platforms are narrower than Fakturownia.

Price: From approximately PLN 39/month; genuinely flat pricing is a real advantage.

Verdict: Solid value for cost-conscious businesses willing to trade a modern interface for predictable, all-inclusive pricing.

6. Aplikacja Podatnika KSeF (Ministry of Finance)

Best for: Businesses that issue very few invoices and want to comply with KSeF at zero cost.

Strengths: Free. Government-issued. Definitionally KSeF-compliant — it is the reference implementation. No subscription, no per-invoice cost, no vendor risk.

Weaknesses: Minimal. It issues invoices and sends them to KSeF. That is approximately where the feature list ends. There is no client management, no recurring invoices, no payment tracking, no reminders, no accounting, no reporting, no customisable templates. It is a compliance tool, not a business tool.

Price: Free.

Verdict: Use it only if you issue two or three invoices a year and have no other needs. For any real business, the missing features will cost more in time than any paid subscription.

Summary Comparison

Tool	KSeF	Ease of Use	Accounting Depth	Reminder Automation	Mobile App	Starting Price
Terminovo	Yes	High	Invoicing only	Excellent	No native app	Free
Fakturownia	Yes	Medium–High	Invoicing + integrations	Basic	Good	~PLN 19/mo
inFakt	Yes	Very High	Invoicing + optional accountant	Basic	Good	Free / ~PLN 250/mo
wFirma	Yes	Medium	Full cloud accounting	Basic	Functional	~PLN 49/mo
iFirma	Yes	Medium	Full accounting	None	Limited	~PLN 39/mo
Aplikacja Podatnika	Yes	Medium	None	None	No	Free

How to Choose

The right tool depends on what you need beyond basic invoicing:

• Need payment reminders built in? Terminovo is the only tool on this list with dedicated, automated payment recovery as a core feature.
• Need full accounting? wFirma or iFirma, depending on whether you want modern UX or flat pricing.
• Sole trader who wants zero accounting headache? inFakt with the accountant add-on.
• High invoice volume with complex types? Fakturownia's feature breadth and API ecosystem.
• Near-zero invoicing volume? Aplikacja Podatnika gets the job done at no cost.

All six tools listed here support KSeF. The differentiator is what else they do. Pick the tool that covers your weakest point — whether that is accounting, payment follow-up, or simply usability — and you will be ahead of most Polish SMEs still managing invoices in spreadsheets.