What Are APIs and How Do They Work?

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APIs are used to abstract the complexity of back-end logic in a variety of software systems. To this effect, API examples are littered throughout your everyday life, whether you know it or not. 

This is because APIs are the primary software infrastructure ensuring that distinct software can work in unison.

Before today, you may have not realized how important it is for software to work together or how often it’s really happening behind the scenes. 

Now you will learn exactly what an API is and how APIs work. In addition, you will be introduced to seven common API examples, including:

  1. Twitter Bots
  2. Log-In Using XYZ
  3. Weather Snippers
  4. Pay with PayPal
  5. Google Maps
  6. Travel Booking
  7. E-Commerce

This piece will deepen your understanding of APIs and its practical use in the software industry. Keep reading to learn more!

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What Is an API?

What are APIs? An application programming interface (API) defines how two or more technologies communicate with one another. 

A happy, anthropomorphic yellow browser window with a green header, eyes, and a smile, with a shiny star to the side, on a white background.

This occurs on the back-end side of development, meaning it’s one of the processes end users are typically unaware of. 

In practice, an API is a hefty block of code that empowers developers to build user-friendly software. 

Still, the use of APIs as part of the software development process is a feat of the modern technology-driven world. 

Here are a few examples of how APIs operate:

  • Looking for a flight for your next getaway? Surely, a quick Google search, putting in the keywords from destination A to B will prompt a convenient snippet of search engine results featuring outputs from different airlines pulled from all over the internet. 
  • Perhaps you’re finally ready to check out your online shopping cart on eBay. Too tired to put in your whole credit card number? No worries. You can purchase your items through the PayPal app embedded into the checkout process.
  • Feeling peckish and need a bite to eat? Peruse Yelp for the best local food spots, click on the address, and it’ll take you straight to Google Maps. 
  • Need to play your favorite song from Spotify? Ask Siri and she’ll make it happen without a second thought. 

All these things happen on account of API integration connecting machines of different capacities and abilities together. While humans connect to these machines in a tangible way, APIs connect machines to each other and provide services like the examples above. 

Metaphorically, you can think of APIs as a user interface (UI) for machines to interact with. That is, it is the front-facing component for technologies on the back-end. 

Related reading: Know The Top 7 API Integration Tools

How Does an API Work?

On the surface, an API might look like a block of code. But in reality, APIs are much more.

On the back-end, APIs sit in the middle of the application and the server. The user asks the application to perform a task and the application uses the API to meet the demand. The API, in turn, must send a call to the server in order to make a formal request.

Simplified graphic of a laptop connected to a rack server with blue and green lines representing an API connection, on a light grey surface against a white background.

Essentially, APIs must know how to talk to the databases and servers they pull data from every time a request is made. Specific actions trigger these reactions from the API like Googling a flight, for example. 

A common abstraction to explain, “How do APIs work?” is a waiter. A waiter is the non-technical version of an API. Waiters take orders from customers and bring them to the kitchen, delivering the final product to the customer. 

What Are the Advantages of APIs?

There are numerous advantages to working with APIs, so many that you probably don’t even realize that you’re already working with an API right now and reaping the benefits. Here’s a quick breakdown of the main advantages of APIs. 


One of the biggest advantages of APIs lies in the answer to the question, “How do APIs work?” APIs foster connectivity between multiple technological systems. 

This modernized way of eliciting functionality abstracts the relationship between code and the service it provides in an intuitive way. To that effect, the abstraction results in practical API integrations that are easier to implement than otherwise. 


Through automation, developers are guaranteed speed. Speed is an integral part of improving apps, services, and development in general. 

APIs automate tasks that would have to be programmed manually without APIs. The connection itself becomes more efficient because it does not rely on the tenacious, fast-typing labor of coders to use a pre-existing function. 


Most would agree that APIs are one of the best avenues for digital transformation. Many of the examples you read above demonstrated exactly how APIs connect cloud apps and combine the different capabilities of several different technologies. 

Gone are the days where you needed a separate device to serve you for every little thing that you wanted to do. What are APIs, you ask? They’re tools of convenience and transformation. 

What Are the Types of APIs?

APIs, like almost everything else on this earth, are diverse. In the context of web development, there are roughly four different API types.

A minimalist infographic listing different types of APIs: REST, SOAP, XML-RPC, JSON-RPC, with each type in a separate white box and the source credit to Trio's API guide.


Representational State Transfer (REST) is definitely the most well-known web API. Hardly any web developer can get through a conversation in the modern age without it being mentioned at least once. 

Unlike other common APIs, REST is an architectural pattern, not a protocol. It is a set of constraints for creating web services, particularly interactive applications. REST uses a subset of HyperText Transfer Protocol (HTTP).


Simple Object Access Protocol (SOAP) has been less popular since REST came around. While REST works with plain text, XML, HTML, and JSON, SOAP only uses Extensible Markup Language (XML) as a format to transfer data. 

SOAP is a means of structuring messages and other communication for web services. Ultimately, SOAP allows different operating systems to communicate with each other, like Linux and Windows


XML-RPC is a type of remote procedure call (RPC) protocol. Its functionality permits programs to make procedure calls across a network.

The protocol utilizes XML to encode the call and HTTP for transport. XML-RPC is relatively old, first originating in 1998, and it’s since been largely superseded by SOAP.


JSON-RPC is similar to XML-RPC, but this RPC uses JavaScript Object Notation (JSON) instead of XML. 

What Are APIs Used For?  

There are two principal use cases for APIs: internally and externally. Internal APIs are alternatively called private APIs. While external APIs can be used interchangeably with open APIs. 

Internally, software development teams may use APIs to ease development from the inside out. For instance, internal teams can utilize APIs to build features for their customers and/or share resources. 

Companies of any kind have moving parts that cannot be publicly shared. Internal APIs are pretty standard to software development companies. But no one outside the company can say exactly what they are. 

Still, private APIs significantly reduce development time by connecting different back-end systems and improving application functionality. 

External APIs are designed to be widely accessible. Developers from a certain company may have published their APIs in the public sphere. Or developers can release non-company-specific APIs publicly.

Open APIs are put to use largely in the same way internal APIs are. Though just about anybody who knows how to use them can access external APIs, they have the same aim as internal APIs in that they speed up development. 

In simpler terms, APIs are used for automating programming processes. Instead of coding line by line the function or program that will connect two technologies, you can simply plug an API towards the same purpose. 

7 Examples of APIs

To be fair, it’s a bit difficult to truly understand application programming interfaces without knowing their real-life applications. Below are seven API examples, demonstrating various types of APIs.

1. Twitter Bots

If you spend a significant amount of time on Twitter, then you’ve probably come across a bot at one point or another. Twitter has numerous bots that utilize the Twitter API to perform automated tasks.

Over a decade ago, Twitter bots accounted for 24% of tweets. No doubt today, their involvement is even greater. There are so many bots it’s hard to find which ones stick out more than the others.

But for the purpose of giving API examples, it’s worth discussing one or two notable Twitter bots.

One fan favorite is @MagicRealismBot, a Twitter bot that generates magical stories every four hours. It uses a random combination of genre-defining elements and plugs them into a 280-character tweet.

A mock social media post from 'Magic Realism Bot' featuring text that reads

@MagicRealism is a Twitter bot fan favorite that generates surreal stories intermittently. 

A more utilitarian Twitter bot is called @ThreadReaderApp. ‘

Twitter users can tag the bot under any thread. Then, the bot wraps up all the text from the thread and presents it as normal, readable text on a page.

Both these bots take advantage of the Twitter API to work successfully with Twitter’s interior software system.

2. Log-In Using XYZ

Okay, so there’s a fair chance you don’t have an account on any platform called “XYZ”. No worries.

Really, the idea is that to sign up for or log into virtually any online service you now have the option to avoid managing a secular account with its own data.

To be clear, surely there are a variety of circumstances where you’ve clicked “log-in using Facebook” or “log-in using Google”.

The effort of creating a whole new account for a certain platform just didn’t seem worth it. Luckily, there was a workaround readily available.

But you have to remember that whichever platform you were on doesn’t just happen to be best friends with Google, Facebook, Twitter, or any other social account.

Even logging in with your information from other platforms requires an API to connect the two platforms together. This is an API example in its natural habitat.

3. Weather Snippets

Ever do a Google search for the weather? A good search input likely resulted in a pop-up weather snippet right front and center on your Google search page.

This is a common Google feature that many smartphone users put to use every day, if not several times a day. It’s also a convenience many have taken for granted.

This is because weather snippets are a prime API example, showing how Google coordinates with other software on the web.

4. Pay with PayPal

Another popular API example is PayPal. PayPal is a fintech service that allows users to connect personal financial information to their PayPal account. This paves the way for easier, more secure money transfers.

You’ll see PayPal intentionally embedded into any number of websites that require financial transactions, from eBay to Airbnb.

The websites interacting with PayPal will not have direct access to your bank or card info. Your security in this regard is because of API integrations.

5. Google Maps

The Google Maps API gives users the privilege of nearly limitless geographic aptitude at their fingertips. Search nearby restaurants, niche shops, and whatever else is in relative distance to your location.

You may have been using this API example more often than you realize. Each time you glimpsed business hours, reviews, contact information, or anything of that nature from that handy box on your screen, that is the Google Maps API in action.

To that same effect, clicking on the map icon in that box will open the Google Maps app for you or take you straight to the Google Maps website.

6. Travel Booking

Travel booking is a very useful API example because making connections and building relationships is exactly the point of most travel websites.

That is, travel websites like Trivago and Expedia have the power to feature and sell all-inclusive travel packages that account for both lodging and travel.

But it’s not just a coincidence that travel booking platforms can pull flight information from American Airlines and book you nights at the Marriott.

No, this is the honest, hard work of application programming interfaces.

7. E-commerce

E-commerce involves the act of conducting commercial activities like buying and selling products online. PayPal, for one, is a service almost emblematic of e-commerce. And Amazon and Facebook both have trademark marketplaces representative of e-commerce.

In general, APIs are a big part of e-commerce, providing e-commerce platforms with security, speed, and scalability. Functions of e-commerce platforms like site search and currency conversion require APIs to operate properly.

Microservice architecture is also integral to e-commerce. Many e-commerce platforms use microservices to encapsulate functionality into separate, independently deployable services.

Such a means of application development offers decentralization and business capability that a monolithic architecture simply cannot.

But the most important bit to note here is that microservices — being independently deployable and all — come together in a single application via APIs.

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The average website visitor whose interest doesn’t go past the visible effects of front-end web development does not often inquire about APIs. Yet, everything that happens on the front-end looks sleek and behaves exceptionally due to back-end technologies like APIs. 

APIs have a great impact on how technology operates today and its impact will likely only grow in the future. Whatever your next project is, no doubt APIs will be involved. 

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With over 10 years of experience in software outsourcing, Alex has assisted in building high-performance teams before co-founding Trio with his partner Daniel. Today he enjoys helping people hire the best software developers from Latin America and writing great content on how to do that!
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