Generally, the REST API calls consist of three steps for accessing the resources.
1. Send a request for the authentication token using the Authentication Service.
2. Receive the authentication token.
3. Use the token for making the API request for any resource.
Plugins for doing REST based calls (REST Client)
Chrome --> Advanced REST client, Postman - REST client, Simple REST client
Firefox --> RESTClient
For validating or formatting JSON --> http://jsonlint.com/