Sharepoint Online Authentication for API Access using POSTMAN

Objective: We know most of the collaboration part of sharepoint has been pushed to Teams, with its planner, conversations, a dedicated site for document uploads and many other features.
So the sharepoint site is now used mostly for document management. Being said that how we can accomodate SPO API for other applications.

In this post we will use SP Online OOTB API to upload and download a file. We dont need to write a seperate application for this, instead we will use POSTMAN to interpret the calls.

When API is avilable OOTB why do we need this post?
Well Service API is available OOTB, but there is specific way we need to authenticate to use that API. That is what we are going to show here.

Let me give a highlevel overview of how authentication works in Office365 Sharepoint site in this case.

OAuth Basics

CodeProject
This sure looks like a Branded Car Logo . . . Isn't it.

No, this represents the new authentication mechanism on which most of the sites are working today.

OAuth - Open Authentication.

I love Valet key example. Many luxury cars come with a valet key. It is a special key you give the parking attendant and unlike your regular key, will only allow the car to be driven a short distance while blocking access to the trunk and the onboard cell phone. Regardless of the restrictions the valet key imposes, the idea is very clever. You give someone limited access to your car with a special key, while using another key to unlock everything else.