The Compatibility Checker helps users determine whether two open-source licences can be used together in a software project and under which licence(s) the project can be distributed. It checks if code licensed under one licence (inbound) can be reused, modified, or distributed under another licence (outbound), and highlights any legal limitations. 

Go to the Licensing Assistant and click on the Compatibility Checker tab in the top menu. 

The tool will display a list of available licences. 

Before using the tool, identify the two licences you wish to compare: 

• The inbound licence is the licence of the third-party source code you plan to reuse in your project. 
• The outbound licence is the licence you intend to apply to your own software when distributing it. 

You must select one licence as inbound and the other as outbound – the checker only works with a pair of two distinct licences. 

In the list of licences: 

• Click the radio button next to Inbound for the licence that applies to the reused source code. 
• Click the radio button next to Outbound for the licence you wish to apply to your own software. 

Then, click the “Check compatibility” button next to either licence. 

The tool will generate a compatibility statement explaining whether and under which conditions the licences are compatible. This includes: 

• Whether redistribution is allowed 
• If additional obligations apply (e.g. attribution, same licence terms) 
• Any limitations or disclaimers 

The Compatibility Checker works best when combined with the Licensing Assistant, which allows you to explore, filter, and compare licences before running compatibility checks. 

For step-by-step guidance on that tool, refer to this article on How to compare and select licences.