What is an API & How APIs Work? An In-Depth Guide

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An API is an interface that functions as a link between an application and other applications, or between a client and a server, to enable feature integration without having to add data manually.

Simply put, the role of an API is like an interpreter or translator who helps two people from different countries and languages communicate with each other.

This API function is very important in applications, because it can help communicate your product or service with other services without having to bother implementing it from scratch.

So, to help you better understand what an API is, we have prepared this article which will discuss the meaning of an API, how it works, API functions and benefits, as well as the various types. Happy reading!

What is an API?

What is an API?
What is an API?

API is an abbreviation of Application Programming Interface. API itself is an interface that can connect one application with other applications. In other words, the role of an API is as an intermediary between various different applications, either within the same platform or across platforms.

An analogy that can be used to explain API is a waiter in a restaurant. The waiter's job is to connect restaurant guests with the chef. So, guests simply order food according to the existing menu list and the waiter informs the chef. Later, the waiter will return to the guest with dishes that are ready according to order.

The abbreviation for API is Application Programming Interface. The use of an API is as an intermediary for several applications or clients and servers, both on the same platform and across platforms, so they can communicate with each other.

API creates integration so that features between the two applications can be connected and displayed in each application. So, later, an application can access the features, services, data, or OS of other applications connected to it.

The existence of APIs certainly helps increase flexibility in simplifying design, administration, use, and provides opportunities for innovation. Yes, innovation for websites or applications is very important to be able to compete in the digital market, and APIs are here to fulfill this task.

Apart from the application itself, APIs are also very useful for helping programmers simplify the application development process, which in the end can increase time and cost efficiency.

For programmers and web developers, APIs make tasks and work easier because they can be used as a communication tool with different programming languages. Developers don't need to provide all the data themselves, just fetch data from other platforms via API. Next, after explaining what an API is, we will discuss its uses and benefits.

How does API work?

After understanding what an API is and its types, we will now discuss how an API works. In the process of carrying out work, the API will carry out several stages from the beginning to producing results.

Here's how the API works:

1. The application accesses the API. 

First, the API will start its work when the user opens the application. For example, a user opens an online ticket booking application and wants to access a specific destination. Here, the application will access the airline API to which it has been connected.

2. The API makes requests to the server. 

Once the application successfully accesses the API address, the request will be forwarded to the airline server. So, the API will convey that the application needs data for the requested flight date and destination.

3. The server responds to the API. 

After the data is found according to the request, the server will return to the API, then provide data in the form of seat availability, departure time, and others.

4. The API provides results to the Application. 

Finally, the information will be provided to the applications the user is accessing. This process occurs with requests to other airlines; So, sometimes the application can display schedules from various airlines at once in one request.

What are the benefits of API?

The API is especially helpful for developers. Because APIs can increase time efficiency, flexibility and save costs. Apart from that, there are also a number of other uses.

Here are the benefits of the API:

1. Makes it easier to create functional applications

The use of APIs is very necessary to create functional and complex applications. Because, applications developed based on the API will automatically have the features provided by the target application, without the need to add data manually.

An example is this.

In online motorcycle taxi transportation applications that provide many services, you will definitely need maps functionality. So, here, online transportation/motorcycle taxi application developers don't need to create their own maps application, they just need to take data from Google Maps.

2. Application Development Efficiency

Both application developers and users want to be able to use various platforms easily. This convenience can be achieved with good communication between applications. Here, the use of APIs is that developers don't need to bother establishing communication with the applications they want to connect to.

Then, APIs are also useful if developers want to build cross-platform applications with various services at once, such as online ticket booking applications/websites. They simply integrate with each service, for example airlines. So, developers don't need manual communication to ask about prices and seat availability on planes.

3. Lighten Server Load

All the data needed on the server does not need to be stored in its entirety because there is an API. Simply query the API to obtain the latest data from the source application server. This convenience will certainly be very helpful because the server will not be burdened and minimize website down-time.

The positive impact will also certainly be significant, because a down server can reduce website performance and make website visitors less comfortable.

So, the lighter server load will also be beneficial for website owners, as well as website visitors who will feel more comfortable when accessing the website.

What are types of APIs?

What are types of APIs?

APIs are grouped based on their access rights. As we discussed earlier, an API is an interface that acts as a connector. In this case, the API is given special privileges that limit the extent to which such connections can be made.

The types of APIs that are commonly used are:

1. Public API

As the name suggests, Public API is a type of API that can be used by anyone on various platforms. Public APIs are also often referred to as Open APIs, and are the most frequently used. If you are a developer, you can directly register or use it in your application.

2. Private API

In contrast to Public APIs which can be used by anyone, Private APIs cannot be used publicly. This type of API is usually used for personal or internal purposes in developing certain applications. For example, the API from the backend is used to access the frontend of a website.

3. API Partners

Partner APIs may be used in general, but only by parties who collaborate and have permission to use them. Like Public APIs, the registration process with the API provider must be done first. Then, its use is only permitted for certain applications according to the agreement.

4. Composite API

Lastly, Composite API is a type of API that stores data from multiple servers or hosting in one place. Of course, this type can help save time and is very beneficial for users because it really shortens the work, namely just one access to obtain a certain amount of data.

What are API architectures?

There are three API architectures that are often used by developers in application development. Well, this architecture is related to the form of data sent. So, what are the frequently used API architectures?

1. RPC

RPC is a technology to make communication between client side and server side possible with a simple concept. RPC has two types, namely XML-RPC and JSON-RPC. As the name suggests, XML-RPC is a type of RPC that uses XML format as a data transfer medium, while JSON-RPC uses JSON for data transfer.

The advantages of REST lie in its simplicity of implementation and good scalability. On the other hand, disadvantages of REST include a lack of consistent standards in API development, a lack of flexibility in managing custom requests, and scalability issues as applications grow large.


Another API architecture is SOAP (Simple Object Access Protocol). SOAP uses the XML format for data exchange and defines a consistent message structure. In SOAP, API operations are described in Web Services Description Language (WSDL).

The advantages of SOAP are strong support for security, reliable message delivery over different protocols, and support for complex transactions. However, SOAP implementations tend to be more complex and have higher overhead compared to REST.


REST or Representational State Transfer is an API architecture that is quite popular because of its ease of use. No need to learn lengthy coding to use it. REST uses JSON as the data form so it is lighter. Application performance is also better.

The advantages of RPC include fast performance, simple implementation, and support for various programming languages. However, this does not mean that this API architecture does not have weaknesses.

Disadvantages of RPC include high dependency on the protocol used and complexity in terms of management. So, this RPC API architecture will be more appropriate if used by medium-sized businesses tending to be large.

4. GraphQL

GraphQL is a query language that allows users to retrieve data with high precision. With GraphQL, users can request only the data they need and avoid over-fetching or under-fetching. Apart from that, GraphQL also allows users to make multiple requests in one request.

The advantage of GraphQL is its flexibility to organize and retrieve data, allowing developers to design more efficient and adaptive API interfaces. GraphQL's disadvantages include a steep learning curve for new developers, a tendency to over-fetch or under-fetch if it is not designed well, and limitations in dealing with complex queries.

5. Apache Kafka

Apache Kafka is a streaming platform used to build systems that can send and receive data in real-time. This API architecture allows asynchronous communication between applications. Kafka is often used in systems that require streaming data, such as log processing, notification systems, and data analysis.

The advantages of Apache Kafka are its high scalability and durability and high support for real-time data processing. However, this API architecture requires a fairly complicated initial configuration process. So, you need special power to operate it so that it runs optimally.

6. Async API

Async API (Asynchronous API) is an API architecture designed for asynchronous (asynchronous) communication. In Async API, messages are sent indirectly through message queues or other intermediary systems. This architecture is suitable for systems that require the exchange of messages without requiring an immediate response.

The advantage of the Async API is its ability to handle high loads and increase application responsiveness, as well as allowing looser integration between applications. Disadvantages of Async APIs include configuration complexity, complex transaction coordination, complex error management, and more difficult monitoring and debugging.

What is the difference between API and web services?

After seeing the explanation above, there may still be some people who don't know the difference between API and web services.

According to Geeks for Geeks, a web service is any service that may be accessed via the internet and the correspondence is carried out through XML coding. The user sends a request (described in XML), then the website sends a response also via XML.

The API itself is an interface used by one service with another to 'communicate' with each other. Actually, the difference between API and web service is quite basic, namely web service is part of API.

So, web services are a form of API that must be accessed via internet services. All web services are part of the API, but the API is not a web service.

What are some examples of an API?

APIs are used in various applications that we often use every day. Here are some examples of popular API uses.

1. Google Search

The Google Search API allows developers to integrate Google search results into their applications. So, the search results that appear in the user's application will be based on things searched for on the Google search engine.

For example, by using the Google Search API, e-commerce application developers can create search features to make it easier for users to search for products. The product search results and recommendations displayed are usually based on things that users are looking for on the platform or other related ones.

2. Weather Widget

Nowadays there are many websites and applications that provide weather forecasts. To make this happen, of course these websites and applications use weather APIs so that the latest weather information can be provided to their users.

By using a weather API, they can pull weather data from trusted sources and display it in an easy-to-read display. For example, weather applications on smartphones usually take weather data from the weather API and display information such as temperature, humidity, and weather forecasts.

3. Log in with a social media account

Many apps or websites allow users to log in using social media accounts, such as Facebook or Google. You are certainly familiar with this event, right? For example, you prefer to log in to Twitter using your Google account rather than creating a new account.

The use of APIs on social media is aimed at authenticating users and retrieving basic information, such as names and profile pictures. That way, the application can shorten the registration or sign-in process, so that users can immediately share content easily and practically.

4. Twitter Bots

Twitter bots use the Twitter API to automatically send and receive tweets, follow users, or perform other actions on the Twitter platform. The Twitter API allows developers to access Twitter features from their own applications.

An example of using the API in a Twitter application is a Twitter bot that can be programmed to respond automatically to mentions. You can try this by replying to people's tweets by mentioning a Twitter bot account. Later, they will provide an automatic answer, related to the tweet you replied to. Apart from that, Twitter bots can also be used to record certain data based on specified keywords.

5. Booking tickets and hotels

As previously explained, OTA (Online Travel Agent) services such as Traveloka or Agoda of course use APIs from airlines, train companies and hotels so that application users can make direct bookings without needing to install applications from these various accommodations.

By using APIs, users can see real-time ticket or hotel room availability, compare prices, and make reservations easily. Another word is that this API connects OTA services with transportation or accommodation service providers and delivers them directly to users.


You've learned what an API is, its benefits, and how it works. It cannot be denied, API is a very useful solution in various ways and for almost everyone, both developers and users.

The global market and digital market that continues to grow today also requires developers to continue to compete to develop applications that are easy to use and can be developed as efficiently as possible.

Well, API or Application Programming Interface can help make all this happen, including helping encourage innovation.

Hopefully, after reading this article, you already understand the definition of an API and the basic things about it. If you still have questions or information you want to convey, please submit them in the comments column below.

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