⚠️ Important: KSeF will become mandatory for large taxpayers on 1 February 2026, and for everyone else on 1 April 2026. Start your integration now! The main client class for interacting with KSeF API.

Building your very first REST API might sound like a big task, but honestly, it’s more about getting started and learning as you go. Think of it like learning to cook; you start with simple recipes, ...