Our API integration services connect your shop, ERP, CRM, payments, Allegro (Poland's largest online marketplace) and KSeF, Poland's National e-Invoicing System, so that orders, invoices and statuses move between systems without being retyped. If a system has API documentation, we can integrate with it.
What is API integration? It is a connection in which programmes exchange data on their own. Among other things, we connect:
Sending invoices in the FA(3) structure from your system and downloading purchase invoices without logging in to KSeF, Poland's National e-Invoicing System, by hand.
Orders and statuses from your online shop inside your own system, and invoices attached automatically to orders on Allegro.
With our ERP integration services, documents, business partners and stock levels stay synchronised between your ERP, accounting software and shop.
Enquiries from forms go straight into your CRM together with their source, and your salesperson can see the customer's orders and invoices.
Payment gateways and recurring payments that change the order status and send a confirmation on their own.
If your system has no API, we design one so that other tools can connect to it securely.
Integration is usually the first step towards process automation: once data flows on its own, the next steps are easy to automate.
Poland's National e-Invoicing System (KSeF) is mandatory from 1 February 2026 for companies with sales above PLN 200 million in 2024, and from that date all companies receive invoices through it. From 1 April 2026 the remaining Polish VAT payers issue invoices in KSeF, and from 1 January 2027 the smallest companies with sales of up to PLN 10,000 per month do so as well.
There are no penalties until the end of 2026. From 1 January 2027, failing to issue an invoice in KSeF carries a penalty of up to 100% of the VAT amount on the invoice, and up to 18.7% of the gross amount for invoices without VAT.
We do not advise on tax matters. Confirm the scope of your company's obligations with your accountants, and we will take care of the technical side.
We work on an hourly basis: programming €46/h net (excl. VAT). The API integration cost depends on the number of systems being connected, the quality of their API documentation and the number of exceptions to handle.
Euro amounts converted at the NBP mid-market rate of 14 September 2026 (€1 = 4.3391 zł) and rounded. We invoice in PLN.
An API is a documented way for programmes to exchange data. With API integration, your systems send and retrieve information such as orders or invoices on their own, instead of you retyping it by hand.
There are ways to do it: importing and exporting files, connecting to the database, or a new API built on top of the system. First we check which route will be stable in your case.
From 1 February 2026 for companies with sales above PLN 200 million in 2024, from 1 April 2026 for the remaining Polish VAT payers, and from 1 January 2027 for the smallest companies with sales of up to PLN 10,000 per month. Penalties apply from 1 January 2027.
The cost is the number of hours times €46 net (excl. VAT). The number of hours depends on where the invoices are created, how many there are and whether the system has an API. We give you a price range within 2–3 working days of reviewing the system.
Yes. The Allegro API allows up to 10 PDF invoices per order, each up to 3 MB, so the invoice from your system reaches the buyer without any manual uploading.
Describe them in the project brief. We reply within one working day, and prepare a price range and a schedule within 2–3 working days.
Fill in the brief