I’ve been working with NetSuite Suite Bundler since 2015. At the time authentication to NetSuite’s API or NetSuite’s RESTlet was accomplished by sending a username and password with each call to NetSuite. If you’re just getting started be sure to read Netsuite API Developer’s Guide first.
NetSuite (I think in 2017) changed this to also allow Access Token based authentication, instead of a raw username/password. As of January 2019, this is now required; the old username/password mechanism has official been deprecated.
Let’s explore how to make API calls with the Access Token based authentication.