API Definition

API (Application Programming Interface) is a piece of software that acts as a middleman between two systems. In order for them to communicate, the API has to follow defined protocols and routines to make it possible for two separate systems to understand each other. APIs are becoming increasingly vital for modern ecosystems, allowing developers to build new interactions between various applications that individuals and companies use on a daily basis. Also, enterprises can integrate their systems with third-party micro-services and do not have to code their own solutions from scratch paving the way for the new standard in modern computing ecosystems based on MACH principles. 

API consists of three key components:

• Routines – routines define specific tasks or functions performed by the API.
• Protocols – protocols define the format used to exchange data between applications.
• Tools – tools are similar to segments from which new API interfaces can be built.

How does the API work?

Technically, API is a code that controls all of the application's or server's access points. API send requests to the application and allow it to send back responses in a format that is understandable to all parties involved. A single interaction between an API and an external system is called an API call. Whereas, a point at which an API connects with the software program is called an endpoint.

API plays a very important role in a modern internet infrastructure that relies on different distributed systems running at the same time. They all need to be able to exchange information quickly. Without API, users would have to constantly juggle between different applications to manually execute desired functions.

For more information on Voucherify API, visit our documentation. 

Types of API architectures

• REST API – REST APIs have gained popularity recently as part of web services. They are designed to make requests and receive responses using HTTP functions. There are four different HTTP commands that REST relies on – GET, PUT, POST, and DELETE. 
• SOAP API – While REST dictates a certain architecture, SOAP is a protocol that follows different standards. SOAP is dependent on XML-based systems and programming. It also usually requires more data to function properly. The SOAP API provides a high level of security. For this reason, it is often used in application programming interfaces intended for financial institutions.

We can also differentiate between client-side and server-side API. A client-side web API is a programmatic interface to extend functionality within a web browser or other HTTP client. Something that is client-side means it is being executed within your application context. On the other hand, a server-side web API is a programmatic interface consisting of one or more publicly exposed endpoints to a defined request-response message system, typically expressed in JSON or XML, which is exposed via the web – most commonly by means of an HTTP-based web server. Server-side means the API call will be executed from another machine or server.

What are the most common API types?

Most typically, APIs can be split based on their purpose or the relationship between the systems they connect: 

• Internal APIs – APIs that connect different systems within a single organization. 
• Partner APIs – APIs that connect separate software from at least two different businesses, usually with the goal of offering additional functionality via integration with another service.
• Public APIs – APIs that are available to any interested party and encourage third parties to connect their system with the open API. 

What is an API-first approach?

Currently, many tech-driven companies adopt the API-first approach which means that they focus on developing their APIs and API integrations with external micro-services, instead of building additional functionalities from scratch. This approach allows for bigger flexibility, faster implementation of new features, and overall better control over the core product. 

Voucherify is an API-driven company – our promotion functionalities are accessible via a well-documented REST API that can be connected with an external application in hours. 

What are the benefits of using APIs?

• Content personalization – APIs make it possible to understand customer preferences. This helps in creating personalized recommendations and hence leads to better interactions with customers.
• Automation – with APIs you don't have to do everything yourself. The API will relieve you of many tedious development and maintenance tasks, thanks to which you can allocate resources to core business functions. 
• Fraud prevention – API can have different security levels, so you can be sure that only authorized parties have access to the data generated using it. For example, you can use an API key, an individual identifier that authorizes you to use the API.
• Speed of integration – it is important for your business to evolve over time. If you have an online store, it's worth integrating it with applications that your customers already trust. For example, you can add a Facebook login function. Most of your customers probably have an account on this social platform, so they can quickly create their profile with you. In addition, if your products and services are associated with popular applications, your brand credibility will automatically increase.
• Build new products – you can use various APIs to build a new product from scratch. For example, the Uber app connects Google Maps with its service interface. You can combine several different APIs to create a completely new product.