If you are looking for Device Handler:
https://docs.smartthings.com/en/latest/ref-docs/device-handler-ref.html#httppost
If you are looking for SmartApp:
https://docs.smartthings.com/en/latest/ref-docs/smartapp-ref.html#httppost
These are for POST requests. Consider reading httpGet for GET requests.
I am a newbie here, so I don’t exactly know which one best fit your needs.