Hi@Paco -- Cam from the Intercom Support team here! 

Would you be able to elaborate a bit further on where you’re getting ‘lost’ and what data you’re looking to get about your Leads via API ? Keen to make sure I’m on the same page as you so I can get you the bets answer possible.

Data on Leads is certainly available via API - if you haven’t done so already, this page of our Dev Docs is well worth a read through as it outlines how we define the overarching concept of Contacts and the Lead and User roles that exist within it.