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Konik - Open Source library for ZUGFeRD compliant invoicing

Contains everything you need for easy ZUGFeRD invoicing input and output.

Reasons to use Konik for ZUGFeRD compliant invoices

Open Source

First open source library to easily create, read, and validate ZUGFeRD invoices for the JVM. See license details.

Beyond the obvious

Easily understandable API which is also well documented. Validation of the invoice against the ZUGFeRD definition and country-specific regulations allow you process the invoice without any surprises.

With options to choose

Easy way of invoice appending or extracting. Multiple PDF Carriages allow you to choose the perfect one for your needs.

Quick Start


The easiest way to get started using Konik in your project is with a Dependency Management System that is able to access the Maven Central Repository.

Copy the code snippet in the black box to your project’s pom file.


Not using a Dependency Management System? No Problem. Get the zip package containing compiled binaries, source code, and documentation.

Download Zip Package

Support and Contact

Stack Overflow

If you have a question on how to accomplish a goal with the Konik library or have a different “How to do X” question, please check if a similar question has been asked before. If this is not the case, then you can create a new question. We closely monitor the Konik tags and will answer all of your questions.

Bugs and Features

Found a bug? The fastest way to get it fixed is to create a ticket on GitHub. You can also see if a similar ticket already exists and comment on that. We always try our best to provide a fix for the next release.

The ticketing system is also a perfect place to request a new feature.

Discussion Forum

Are you interested in the Konik library development discussions or would you like to find out more about the ZUGFeRD specification or how to implement electronic invoicing into your product?

Join the Konik Discussion Forum to follow and take part in ongoing discussions about the feature of the library.

You like it more private?

When you think that GitHub and Stack Overflow are not the right places to ask your questions.