API Call

What is an API Call?

An API (Application Programming Interface) Call is a request made by a software application to another service or system, usually to get, send, or manipulate data. It’s how different applications talk to each other.


Techopedia Explains

For example, imagine you’re at a restaurant, and you’re ready to order. Instead of shouting your order directly to the chef in the kitchen, you tell the waiter what you’d like, and they relay your order to the chef. In this scenario, the waiter acts as a go-between, making sure your request is fulfilled. An API call works in a similar way but in the digital world.

API calls allow for seamless integration of various systems, letting them share functionalities and data without having to merge into a single platform. This is why, when you use a social media platform like X (previously Twitter) or Facebook, you can easily share a YouTube video or an article from a news website.

Behind the scenes, API calls are being made to make sure that different platforms can understand and relay information to one another.

How Does an API Call Work?

Understanding how API calls work is essential to understanding how software applications interact and share data. The foundation of an API call is the request-response model:

  • Request: A software application, known as the “client,” sends a request to another system or service, which is referred to as the “server.”
  • Response: Upon receiving the request, the server processes it, gets the necessary information or performs the desired action, and then sends a response back to the client.

Endpoints play an important role in the API interaction. An endpoint is a specific URL where an API can be accessed to carry out a specific operation. It’s essentially an address that directs the client to a specific set of data or functionality on the server.

When making an API call, the chosen endpoint helps determine which action the server should take and on which set of data.

API Call Methods, Explained

API calls allow diverse software applications to communicate and transfer data. One of the foundational elements of these interactions is the method used in the call.

These methods, also known as HTTP methods, determine the type of action that needs to be performed, like getting, creating, updating, or deleting data.

GET Request

A GET request is a method that requests data from a specific resource. It fetches information without causing any side effects, meaning it doesn’t alter or modify the data on the server.

The GET request is one of the most common HTTP methods. When you’re browsing the web and you click on a link to visit a page, you’re often initiating a GET request. This request asks the server to provide the specific webpage or data you’re interested in.

Get Request Examples

  1. When you type a website URL into your browser’s address bar and hit enter, you’re sending a GET request to the server hosting that website, asking it to provide the webpage associated with the URL.
  2. Imagine using a weather app. When you ask for the weather in a specific city, the app sends a GET request to its server to fetch the current weather data for that location.
  3. Search engines, like Google, send a GET request whenever you type a query into the search bar. The request retrieves all the relevant results for your search term.

POST Request

A POST request is used to submit data to a specific resource or server, typically causing a change in state or side effects on the server. It’s the method chosen when the intent is to create or update the data stored on the server.

Unlike GET requests, POST requests don’t append data to the URL. Instead, they include the data in the body of the request.

Post Request Examples

  1. Think of when you sign up for a new social media account. You fill out a form with your details, like username, password, and email. When you hit the “Sign Up” button, a POST request is sent, submitting your information to the server to create your new account.
  2. When you’re shopping online, and you decide to purchase an item, upon entering your shipping details and payment information and then clicking “Purchase,” a POST request is generated. This sends your details to the server, leading to the creation of an order.
  3. You’re gaming on a cloud gaming platform. When you decide to save your progress, your gaming application sends a POST request to the cloud gaming server. It then creates a new save record.

PUT and PATCH Requests

The PUT method is used to update an existing resource or create it if it doesn’t exist. When using PUT, you provide a complete, updated version of the resource. It’s an “all or nothing” approach: if a particular part of the resource is left out in the PUT request, it’s assumed that the omitted part is not required, and it’s removed or reset.

The PATCH method, in contrast, is used to make partial updates to an existing resource. Instead of sending a complete, updated version like with PUT, with PATCH, you only send the specific changes you want to apply to the resource. It’s more about tweaking existing data.

PUT and PATCH Request Examples

  • PUT: You have a profile on a professional networking site like Linkedin, and it has fields for your name, job title, and address. If you use a PUT request to update only your name and job title, leaving out the address, the system would assume you no longer want an address listed and would remove it.
  • PATCH: Using the same professional networking profile example: if you’ve recently changed your job title and want to update just that, you’d use a PATCH request. You send the new job title without including the name or address. The system would update only the job title, leaving the other details unchanged.

DELETE Request

The DELETE request is used to request the removal of a specific resource or data from the server. When used, the server processes the request, deleting the specified data.

Following a successful DELETE operation, the server often returns a status indicating the successful completion, although the actual resource is no longer available.

Delete Request Examples

  1. Have you ever posted something on social media and then decided to remove it later? When you click on the ‘delete’ option, a DELETE request is sent to the server, ensuring the post is removed from the platform.
  2. When deciding to leave a service or platform and choosing the option to deactivate or delete your account, a DELETE request is initiated. This request ensures your account details and associated data are removed from the server.
  3. You’re shopping on Amazon and add items to your online shopping cart but later decide to remove an item. When you click the “remove” button next to an item, a DELETE request is made to the server, removing that item from your cart.

The Importance of API Rate Limits

API rate limits specify the number of API calls an end-user, or a system can make in a set time frame, be it a minute, an hour, or a day. These limits can be set on a per-user basis, per IP address, or even based on the type of service accessing the API.

They act as control measures, ensuring that the API can serve many users without being overwhelmed by too many requests.

Here’s why rate limits are implemented:

  • Performance Maintenance: High traffic can overwhelm servers, leading to slower response times or even crashes. Rate limits ensure that APIs function optimally and consistently, offering reliable service to all users.
  • Resource Allocation: API providers might want to ensure that resources aren’t monopolized by a single user or service. By setting limits, resources are distributed fairly among multiple users.
  • Security: Rate limits can act as a safeguard against malicious attacks, like Distributed Denial of Service (DDoS) attacks, where attackers try to flood the system with requests.
  • Cost Control: Processing large volumes of data can be expensive. Rate limits can help API providers manage and predict operational costs.

The Bottom Line

APIs act as bridges between diverse software systems, allowing them to converse seamlessly, share data, and augment functionalities.

From powering the social media integrations on our favorite apps to the banking transactions we make daily, API calls are at the very heart of these interactions. In essence, they play an instrumental role in shaping the way we experience and interact with digital platforms.


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Marshall Gunnell
IT & Cybersecurity Expert

Marshall, a Mississippi native, is a dedicated expert in IT and cybersecurity with over a decade of experience. Along Techopedia, his bylines can be found on Business Insider, PCWorld, VGKAMI, How-To Geek, and Zapier. His articles have reached a massive readership of over 100 million people. Marshall previously served as the Chief Marketing Officer (CMO) and technical staff writer at StorageReview, providing comprehensive news coverage and detailed product reviews on storage arrays, hard drives, SSDs, and more. He also developed sales strategies based on regional and global market research to identify and create new project initiatives.  Currently, Marshall resides in…