The Gallery of Custom Element samples contains a list of different custom elements that might help you to extend content editing capabilities inside of your Kontent.ai.
A Custom element is essentially a small HTML application that exists in a sandboxed <iframe> and interacts with Kontent.ai via the Custom Elements API.
The Gallery of Custom Element samples contains a list of different custom elements that might help you to extend content editing capabilities inside of your Kontent.ai project, or even connect with different 3rd party services (like Digital Asset Management tools, or eCommerce solutions).
The custom elements denoted as core integration are focusing on a selected subset of integrated services mentioned on https://kontent.ai/integrations. These integrations will have a richer documentation and their issues will be handled with higher priority.