Updated on February 03, 2023

Introduction

You probably have heard about ‘APIs’ a million times by now, But what are they? Why should they matter? and more importantly, how can they help you?

Getting started

In this article, we will cover the following:

  1. What an API is.
  2. How to make API integrations.
  3. How to troubleshoot an error.

What is an API?

An application programming interface or API (as it is fondly called) is an interface that allows you to communicate with other applications and data sets. You can think of APIs as a doorway to another application or data.

When a system wants to share its application with an external system, it would expose API endpoints for that application. This way, other developers can connect their applications to the ‘shared’ application.

APIs power a lot of popular websites, web and mobile apps. They are really helpful in extending functionalities into these apps. Some APIs help you collect payments, get locations on maps and lots more!


How do APIs work?

APIs are a bunch of rules that allow applications to communicate with each other. To understand better why we need these rules, let's take a look at the components involved in this communication:

  1. A User - This is the person who triggers the communication.
  2. A Client - This is an application through which the user sends the communication
  3. A Server - This is usually the computer that houses the application you want to connect with.
A developer would first build the server to hold the application. This server would process and hold application data. Once this is done, the developer would publish documentation that would guide on how other applications can get connected to the server and get its application data.

This API communication is usually in two phases. The first part is called a request. This is from the client to the server. After a request is made, the server then sends back the application data. The communication from the server back to the client is called a response.


What makes an API?

Now that we know what an API is, let’s take a deeper dive into the different parts that make up the API.


Endpoints

An Endpoint is a URL that serves as entry points to an API. You can think of it as a specific URL for a function on a server. For example, to get your account balance with Flutterwave, You need to interact with that part of our application. It is exposed via the URL, https://osb.ng/api/v1/balances/


HTTP Verbs

Just like grammatical verbs, HTTP verbs are actions that an API can make. Today, there are lots of verbs you can use, but we would be focusing on the popular ones.

  1. Get - When the GET method is used with an API request, It allows the user to fetch information from the server. This method is especially useful for querying and downloading information from the application server.
  2. Post - The POST method is the literal opposite of the GET method. This method allows sending information to the server. The method is used mainly for creating a new resource in the server e.g. creating a new payment.
  3. Put - This is only used when the user intends to update existing information (or information sent previously to the server).
  4. Delete - This is only used to permanently remove information from the server. This should be used after careful consideration.


Body Parameters

When sending a POST request, you would need to send some information in the body of this request. Any information that you do not pass in the API URL or header is by default sent in the body of the request.

The body of the request is usually in JSON (JavaScript Object Notation - a dictionary, key-value pair) or XML format.



Query Parameters

Query parameters are parameters found only in the endpoint URL. They are used as filters to fine-tune the data being returned from the server. Query parameters are separated from the main URL by a question mark.


Path Parameters

These parameters behave just like variables in the endpoint URL. They are useful in carrying out dynamic actions on multiple items. For instance, the verify endpoint (https://osb.ng/api/v1/transactions/&id=123456) contains the path parameter - ID. This allows the user to pass the IDs for different transactions to this endpoint.


Working with APIs


Authentication

Most APIs require you to sign up to get a key (this could sometimes be a combination of different keys) to access the server. This is important for several reasons, some include:

  1. To protect the data.
  2. To eliminate the abuse of the data stored or processed on the server.
The API keys help the server identify which user is making a request. This makes account profiling and access to different levels of APIs possible.

When making an API call, always refer to the developer documentation. This would explain how you can get your Keys and authenticate the API requests.


Making an API request

In this section, we'd quickly cover the essentials of making an API request.

Pre-requisites


To get started with your API calls, Here is a helpful checklist to get started.

  1. Sign up and get your API Keys.
  2. Read the Developer docs (Just the API reference for the feature you need is sufficient).
  3. Decide if to make the call via an API client or from your code.


Using an API Client

This is an easy way to start exploring APIs. API clients are tools that can help you in making requests. Popular clients include browsers(e.g. Google Chrome), terminals and custom clients (e.g. Postman, Insomnia).



We wrote these docs assuming you are familiar with APIs and can make API calls. If you are new to the concept of APIs, You should check out our API basics article.