How To Develop An API?

Software developers and programmers should learn how to develop an API. APIs are an important aspect of the entire app development process. Instead of reinventing the wheel and writing different software modules from scratch, programmers now rely on pre-built and pre-tested reliable software. APIs provide a gateway to accessing the services of such tried and tested software modules.

To help you with the API development process, we have compiled this comprehensive guide. It shows you the various steps involved in coding your APIs. Continue reading to discover the various stages and other important factors to consider when developing an API.

What Is An API?

The term API stands for Application Programming Interface. It is an interface of a program or software through which other programs can communicate. It is through this API that software offers services, data, or other functionality.

Why Do I Need APIs?

Developers already know the importance of APIs. APIs bring additional functionality into your software. For many modules, you don’t have to write code from scratch. Moreover, if you are using APIs from a trusted source, you can rest assured that the service or functionality an API provides is robust and reliable.

As an example, if you are building a sales system, you can easily use a powerful API for currency exchange that shows your customers the prices in their local currency. Similarly, you can use an email verification API to verify different email addresses. In both cases, you don’t have to write any program or module from scratch. You can simply use the pre-built and pre-tested software through its APIs.

What Are Some Examples Of APIs?

For examples of APIs, you can look at APILayer’s API marketplace. Here you’ll find numerous APIs that offer some service or capability. For example, there are AI and machine learning APIs through which you can discover emotions in textual messages, classify text into different sentiments, extract the most relevant words or expressions from text, or more. Similarly, there are computer vision APIs, currency conversion APIs, Geo APIs, SEO APIs, and more.

How To Develop An API – What Are The Steps?

If you want to develop your API, then here is a list of steps that you can follow:

1: What Is Your Objective?

The first step in the process of API development is to list your goals and objectives. In this step, you also have to identify who would use your APIs. For example, are you aiming for enterprise customers, individual users, academics, or hobbyists?

Once you have identified your objectives and users, you are in a position to formally write down the functional and non-functional requirements. The functional requirements involve figuring out business logic, technical details, data manipulation, and more. As opposed to this, non-functional requirements specify factors such as usability, security, scalability, and more

2: What Is Your API Architecture?

The next step in the process of API development is to decide your API architecture. For example, you can decide whether to use REST or SOAP.

REST Web API Architecture

REST stands for Representational State Transfer. It is a very popular and accepted industry standard. REST APIs are web-based and allow their users to request data and other resources or functionality through a URL with parameters. They normally return data using JSON or XML.

SOAP API Architecture

SOAP stands for Simple Object Access Protocol. SOAP was introduced so that different programs built using different technologies on different platforms can exchange data. It requires more resources and bandwidth compared to REST. Also, the return data format is XML.

3: What Is Your API Specification?

Once you have figured out your API architecture, you can decide on the API specification. An API specification is a definition of all the calls comprising an API. An individual call associated with an API is also called a method, sub-routine, request, or endpoint. The entire specification consists of the API endpoints and their corresponding parameters.

As an example of endpoints, the currencylayer API uses the endpoint live for requesting the most recent exchange rate and historical for extracting historical values with the date parameter. Here are two examples.

https://api.currencylayer.com/live

https://api.currencylayer.com/historical?date=YYYY-MM-DD

4: What Is Your API Response?

The next step for developing an API is defining your API response. If you are returning data in JSON format, then define the keys and their corresponding values. Likewise, if you want to return data as an XML object, again, you need to define various tags and their corresponding data.

You also need to identify all the status codes that your API might return. For example, an HTTP status code with a value of 200 is generally used to indicate that the API call was successful. On the other hand, the HTTP status code value 400 means “bad request”.

Additionally, you also have to define different errors that can take place during the query/request and their corresponding codes.

5: What Is Your Development Environment?

Once you have a full design of your API, you can choose a development environment or framework. Examples include Swagger, SoapUI, Postman, APIMatic, and more.

6: How to Develop an API – What Are Other Things To Consider?

When developing an API, you have to consider other things, like whether you need pagination. If the response object is too big, you may want to divide your response data into several pages and send each page as requested. You also need to consider the response time of your API and how critical it is to your users. Other important factors are security, data encryption, data compression, client-side caching, and more.

Do you need documentation? Indeed, yes! You should document everything related to your API, all possible endpoints, return status, error codes, and more.

Where Can I Find A Very Extensive List Of APIs?

APILayer is the best API provider with the most comprehensive API list. All of APILayer’s APIs are free to try out! These APIs are trusted by over 1 million developers. If you are satisfied with your free trial, then you can sign up for a paid plan. Start using APILayer’s APIs and be on your way to building awesome apps.