The node-red Integration Server can be accessed by admins from the User dropdown > Integration Server:

This opens up the node-red admin page:

Node-RED has a drag-and-drop editor that lets you set up HTTP endpoints to perform the custom logic you need to power your integrations. You can learn more about node-red here: https://nodered.org/

In the following example, we'll walk through setting up a TeselaGen sequence search integration endpoint (using node-red for the "glue" code): http://docs.teselagen.com/en/articles/4332711-external-integration-dna-sequence-import