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What is a Web API

Posted on:February 24, 2023 at 08:21 PM

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A web API (Application Programming Interface) is a set of programming instructions and protocols used to access a web-based software application or web tool. In simple terms, it is a set of rules and protocols that enable different software applications to communicate and share data with each other over the internet.

Stateless API calls

An API call is considered stateless when it can be made independently from all other requests, with no additional context or data whatsoever e.g., ask for the weather based on the postal code.

Stateful API calls

A web API that stores a user’s favorite cities and provides weather forecasts for those cities requires a user to already have stored the cities, so we can consider an API stateful if:

Resource-oriented APIs

This kind of API provides a standard (limited) set of building blocks. Rely on the idea of “resources”, the key concepts we store and interact with.

Create<Resource>()Allow us to create a new resource
Get<Resource>()Allow us to get a single resource
List<Resources*>()Allow us to get a list of resources
Delete<Resource>()Allow us to delete a resource
Update<Resource>()Allow us to update a resource

*Note that the resource is in the plural form.

What makes an API “good”?

Well, before we explore the different aspects that tend to make APIs “good”, let’s establish two simple reasons about what is the purpose of building an API. Overall, we can say those reasons are:

  1. We have some functionality that our users want.
  2. Those users want to use this functionality programmatically.

What are the desirable qualities of an API?


To summarize, APIs are very useful and it’s important to learn how to design them. In future posts, we’ll explore some design patterns we can use to improve our APIs.