How to Set Up an API for Multiple Clients

The concept of cores, C-O-R-S, cross-origin resource sharing is a fundamental security feature of the web. When you're setting up your API, that can often live on a different server than your front end. You need to specifically say, this front end can access my back end API. If you don't set that, it won't work. It's something people may not have thought about if they're just coming from a web framework world.