Integration with external api

Situation
I need to integrate OpemEmr with an external API through Json, where can I find documentation?

OpenEMR Version
I’m using OpenEMR version 5.0.0
Browser:
I’m using:

Operating System
I’m using:

Logs
Did you check the logs?
Was there anything pertinent in them?
Please paste them here (surround with three backticks (```) for readability.
You can also turn on User Debugging under Administration->Globals->Logging User Debugging Options=>All