| CSOM | JSOM | REST API |
| CSOM(Client Side Object Model) requires Microsoft.SharePoint.Client.Runtime.dll and Microsoft.SharePoint.Client.dll to interact with SharePoint | JSOM(JavaScript Object Model) requires two main libraries sp.runtime.js and sp.js to interact with SharePoint | REST API(Representational State Transfer) does not require any dll or JS library, as it is based on OData protocol, we can use REST API directly to interact with SharePoint |
| CSOM calls are Synchronous | JSOM calls are Asynchronous | REST API calls can be either Synchronous OR Asynchronous |
| When to use: 1) Provide Hosted App (Add-in) 2) .Net application that performs CRUD operation on SharePoint data 3) Batch Processing 4) conditional processing of code and exception handling 5) Working with LINQ | When to use: 1) SharePoint Hosted App(Add-in) 2) Html/JavaScript application that interacts with SharePoint 3) Batch Processing | When to use: 1) SharePoint Hosted App(Add-in) 2) A mobile app/any external system that interacts with SharePoint content |
