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What Is an API Call?

what is an API

APIs (Application Programming Interfaces) have unarguably become a must-have technology for web development. They accelerate web app development by allowing an app to fetch data from a specific database and access the functionality of another app. This means developers don’t have to write code for a particular functionality or create a database for their app from scratch. For this reason, developers worldwide use APIs to develop apps quickly and efficiently. When working with an API, it’s essential to know about commonly associated terms, such as an API call and an API key. In this article, we’ll specifically focus on What is an API call. Then, we’ll also discuss where you can find the best and most reliable APIs. Let’s get started!

What Is an API?

Before we explore what is an API call, let’s first discuss what an API is.

An API enables two apps or software programs to interact or talk to each other. It acts as an intermediary between two systems or apps, allowing one to send data and the other to receive it. Today, developers utilize different types of web APIs to build efficient apps quickly. For example, if you want to create a weather app, you can use a reliable weather API to retrieve real-time and future weather data quickly and display the information on your app. The weather API in the background fetches data from popular weather databases, such as large weather stations.

What Is an API Call?

Now that you know what an API is, let’s focus on what is an API call.

An API call is simply the request that an app sends to an API to receive or retrieve data. In other words, when you use an API endpoint with the API’s base URL to request data, you’re making an API call. For instance, when you open a weather app to view weather forecasts or current weather conditions, you make an API call. Similarly, when you sign up to use an application, you actually make an API call.

An API call is sent to an API endpoint, which then accesses the data from an external source and sends it back to the app that initiated the request.

The steps below show how an API works:

  1. The application makes an API call to fetch data from another program. It is sent as a request to the web server via the URI (Uniform Resource Identifier) of the API.
  2. When the API receives the request, it starts the process of extracting data by calling the web server of the other application or program.
  3. The server sends the requested data in response to the API call.
  4. Next, the web API sends the data back to the client or the app that made the API call. However, APIs can only return specific data or information made public by their developers due to security reasons.

What Are the Different Types of API Calls?

Here are the most common API calls of a REST API:

  • GET: Enables apps/users to fetch data from a server
  • POST: Used for resource collection
  • PUT: Enables users to modify resources
  • DELETE: Deletes or removes existing data or a resource from the server

How to Make an API Call?

What is an API call - Application development using APIs

Here, we’ll demonstrate how to make an API call using APILayer APIs. APILayer is a reliable API marketplace with over 75 APIs for various use cases. These include social media APIs, Geo APIs, finance and currency APIs, a weather API and more. Moreover, new APIs are constantly added to the marketplace. If you’re an API seller, APILayer will manage customer acquisition, payment collection processes, key management, memberships, and rate limits for you.

Making API calls is easy, but you first need to choose your desired API. Next, you need to sign up by providing the necessary details to get your API access token or API key. The API key is a combination of alphanumeric and special characters and is unique to each user. API keys enable APIs to identify the app calling them and verify API clients for security purposes. You must use your API key and your desired API endpoint to make an API call.


For example, you can use APILayer’s Fixer API to get accurate real-time and historical exchange rate data. Here is how you can use the API’s ‘latest’ endpoint to make an API call and get real-time exchange rate data for any currency pair of your choice:

You can click ‘Run API Request’ to get an API response. The REST API returns data in an easy-to-read JSON format that you can integrate into your web applications using the programming language of your choice. You can find all the information related to the API and its endpoint in the API documentation.

Similarly, you can use APILayer’s weatherstack API to get current, future, and historical weather data. Here is how you can use the API’s ‘current’ endpoint to make an API call and get real-time weather data:

Why Use APILayer APIs?

What is an API call- APILayer marketplace

APILayer offers a number of secure APIs. Here are the key reasons why so many developers use APILayer APIs:

  • All the APIs are REST APIs and easy to use.
  • All APIs come with a free plan.
  • APILayer APIs use highly-reliable data sources to provide accurate data.
  • All APIs have detailed documentation to help users get started quickly.
  • APILayer APIs are highly scalable.


An API acts as a middleman between two applications and enables them to talk to each other or exchange information. It speeds up web app development by providing access to existing data or functionality. One key term associated with the use of an API is an API call, which is essentially the request made by an app to retrieve data using the API endpoint. This article discusses in detail what is an API call. If you’re looking for the best and most secure APIs, you can explore the APILayer marketplace.

Sign up for APILayer and try its secure REST APIs today!

Frequently Asked Questions (FAQs)

Why Are API Testing and API Security Important?

API testing ensures the API is working as expected. API security is crucial because it stops cyber attackers from sending API calls to access private data and misuse it.

What Is an Example of an API Call?

Here is an example of an API call made using the weatherstack API ‘current’ endpoint:

https://api.weatherstack.com/current? access_key = YOUR_ACCESS_KEY & query = New York

How Can You Make an API Call?

You can use your desired API endpoint and unique API key to make an API call.

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