An API, or application programming interface, is a set of rules that define how applications or devices can connect to and communicate with each other.
An API needs to meet the following rules to be called a RESTful / REST API.
Client-server: A RESTful API follows the client-server model where the server serves data and clients connect to the server to consume data. You can use Hoppscotch as a client for your API server to build and understand how API is used in the real world.
Stateless: A RESTful API should be stateless. Each request is treated as a standalone request. The server should not keep track of any internal state that might influence future requests.
Uniform interface: All API requests for the same resource should look the same, no matter where the request comes from.
The go-to Open-source tool for building an API would be Hoppscotch (previously known as Postwoman). It is crafted with Vue.js and a minimalistic design. You can save it as a PWA and use it whenever you want, like a desktop or a mobile app. Here is the link for the curious one’s who wants to explore it further. Hoping that this would help you to get started.
Taken originally from u/Aviyelhq via our Subreddit.