The Junction Analytics API is based on REST. It is synchronous, it has resource-oriented URLs, and it uses standard HTTP response codes.
The latitude and longitude coordinates are in EPSG4326 / WGS84 format for both input and output.
These are the only supported coordinate systems.
Endpoints overview - using the API step-by-step
Create a junction definition in the Web App: https://ja.tomtom.com. Learn more about junction definition creation on TomTom Move Support website, link: TomTom Junction Analytics User Guide - Creating a new junction
Wait for the junction definition to be processed - monitor the definition status - Docs.