What is an API

What is an API

August 5, 2022

Apps are a huge part of our life, we use them every day. Even when we are working, we are using corporate applications. But do you know what software is behind these applications and what API security entails?

What does API stand for?

API stands for Application Programming Interface. It allows software applications to interact with each other. An API can also be a connection between computers or between computer programs. It allows applications to access data and interact with external software components, microservices, or operating systems. Every time you use Facebook or check the weather on your phone, you’re using the software-interface.APIs offer a service to other pieces of software. An API specification is a document or standard that describes how to build or use a connection or interface. When a computer system meets this standard it is said to implement or expose an API.An API lists a bunch of operations that developers can use, along with a description of what the APIs do. Developers can provide their own data to the API to get results.The “Application” in API refers to software with a distinct function. “Interface” refers to a contract of service between two different applications. This defines how the two applications communicate with each other using requests and responses.

What are APIs used for?

An API connects computers or other pieces of software to each other. It’s not intended to be used directly by a person. APIs are often made up of different parents which act as services or tools that are available to a programmer. When a developer uses one of these parts, he is said to call that portion of the API. These calls are also known as subroutines, requests, methods, or endpoints. They are defined by an API specification, meaning that it explains how to use or implement them.APIs hide internal details of how a system works. This exposes only the parts a developer finds useful. An API may be custom-built for particular systems or it may be a shared standard.With APIs, developers can take advantage of a platform’s implementation. It helps reduce the number of code developers need to create. It also helps create more consistency across apps and controls access to hardware and software resources.The term ‘microservices’ comes up regularly in relation to APIs. They are a style of architecture that divides functionality within a web application. Microservices can actually use APIs to communicate with each other.

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What is JSON?

In order to send or receive information, developers can make a specific call or request. For most modern APIs this is usually done using a programming language called “JSON”. It can also be used to update or delete data. JSON stands for JavaScript Object Notation, it’s used to represent data on a server. It’s fairly easy to read by humans and easy for computers to understand.

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What is an API request?

The endpoint, header, method, and data are all components of the API request. These components are necessary in order for them to function properly.


Endpoints have two important parts that are used when making an API request, one of which is the URL. The second part is the path. This will vary depending on what you are trying to accomplish. When you put these two parts together, you get a complete endpoint.


A header provides information to the client and the server. Examples of headers would be authentication credentials such as an “Auth Token” or “Client ID”. These authentication credentials are provided to you automatically when you create an API account. Another common header is the “Content-Type” header. It informs the server about what type of content will be sent. An example of a commonly used content type is “application/JSON”. This lets the server know that we’re sending JSON data.


These methods are actions taken when sending a request.Examples are:

  • Get: gathers information
  • Put: updates or creates pieces of data
  • Post: creates
  • Delete: deletes


Data also commonly referred to as “body”, is information that will be either sent to or returned by a server. The body of a request sometimes requires specific information before it can be delivered.

How do APIs work?

API architecture usually refers to the communication between the client and the server. The application that sends the request is called the client. The application that sends the response is called the server.Here’s how APIs work:

  1. The client application initiates an API call to retrieve information. This is also known as a request. The request from the application is processed to the webserver.
  2. The API makes a call to the external program or web server, after receiving a valid request.
  3. The server then sends a response to the API with the information that the client application requested.
  4. Finally, the API transfers the data to the initial requesting client application.

The data transfer will differ depending on the web service you use. This process of requests and responses all happens through an API. APIs are designed to be used by computers. They simplify app development, save time and money, give flexibility, and simplify design, administration, use, and innovation.APIs make the integration of new application components into existing architecture easier. They help business and IT teams collaborate. Businesses need to respond quickly in order to stay competitive. Cloud-native application development can be used to increase development speed. It relies on connecting microservices application architecture through APIs.APIs offer security because they are designed to be a middleman between two systems. This means that the consuming application is separated from the infrastructure providing the service. API calls also usually include authorization credentials that reduce the risk of attacks. During the exchange process, HTTP headers, cookies, or query string parameters provide additional security layers.In short, APIs let you open up access to your resources while you can maintain security and control. You can choose how you open access and to whom. More on API security follows further in this article.

Why do we need APIs?

You can use an API when you’re managing existing tools or designing new ones, to simplify the process. APIs can also help consumers easily find products, grow ecommerce brands, and expand earning potential by selling products on online marketplaces. They have many other benefits.

Improved collaboration

The average company uses around 1000 cloud applications. This way, companies can automate workflows and improve workplace collaboration.

Easier innovation

APIs offer flexibility to make connections with new business partners, offer new services, and access new markets to generate more profit and drive digital transformation.

Data monetization

Many companies choose to initially offer their APIs for free, so they can build an audience of developers and forge relationships with potential business partners. When the API grants access to valuable digital assets, you can monetize it by selling access.

API security

APIs create an additional layer of security between your data and a server. When you use APIs, you send small amounts of information that the API delivers. Then the server sends it back. This way, you aren’t directly linked to a server and it minimizes the risk of a breach.Developers can also further strengthen their API security. APIs often play a big role in security. They are used to control access to hardware devices and software devices that an application might not have access to. An example of this is the geolocation API that asks to see your precise location when you visit a website.


With APIs, everything is easy and fast. Instead of having to go to a store or calling them, you can easily see what a product is, the price, and the stock level. APIs also make the life of developers easier. Every operating system has standard APIs that developers can use for their apps. This is faster and more cost-efficient.


You can grow your online store at a faster rate because you don’t have to factor in new code for expanding your catalog, security, or data needs.

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Examples of APIs we use in our everyday lives

It’s hard to understand APIs without examples, so we have compiled a few examples of APIs that you use on a daily basis. APIs can be used in many different ways.

Universal logins

Universal logins or log-in using XYZ is a popular API example that enables people to log in to websites by using their Facebook, Twitter, Github, or Google profile login details. This API allows any website to quickly authenticate the user. Applications with this API don’t actually log into the users’ social media accounts. This saves them the time and hassle of setting up a new account for every new website visitor.

Third-party payment processing

This API allows people to pay online without exposing sensitive data or granting access to unauthorized individuals. An example of this API is the “Pay with PayPal” functionality. Just like the universal login API, this API is built to ensure that the application can only do what it needs to.It works similarly to the log-in process of the log-in API. The application sends a request to the PayPal API for the specific owed amount. Finally, a pop-up authenticates the user, confirms the purchase and the API sends confirmation of payment back to the application.


Travel booking comparisons

Travel booking sites use APIs to collect flight and hotel availability information from providers to showcase the cheapest option. They will also use APIs to confirm the trip with the provider you booked through. This automates the exchange of data and requests and reduces the time and effort it takes to check for available flights or accommodation.

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Google Maps

The Google Maps service is one of the most common examples of a good API. Not only does it use an API that displays static or interactive maps. It also uses other APIs to provide users with directions or points of interest. Through geolocation and multiple data layers, you can communicate with the API when planning travel routes or tracking vehicles on the move. You can take a look at business hours, reviews, or contact information.


Twitter bots

There is a huge range of bots on Twitter. These bots are accounts that automatically tweet, retweet, follow, and send direct messages based on software instructions. There are Twitter bots that send hourly reminders, bots that identify grammar mistakes, and bots that tweet when new content is released on Netflix. These bots are all powered by the Twitter API.

Weather snippets

The most common API we use every day is the weather snippets. These weather snippets can be found on all platforms like Google Search, Apple’s Weather app, or even from smart home devices. Using this API you will be able to see the current weather conditions and forecast.


E-commerce APIs are used for the act of conducting commercial transactions like buying and selling products online. In this category, there are product information APIs, site search APIs, payment APIs, shipping APIs, and currency conversion APIs.These interfaces are all used to gather data or make calculations during the buying process. Microservice architecture is also very important to encapsulate functionality into separate, independently deployable services. These microservices come together in a single application via APIs.

The history of APIs

When we are talking about APIs, we are most likely referring to web APIs or APIs built using REST. Web APIs have a relatively brief history and they are behind almost every aspect of how we do business online. When we refer to web APIs, we almost always refer to our modern approach.This means using HTTP to provide access to machine-readable data in a JSON or XML format (these are used to share data within the programming languages of operating systems). Companies like eBay, Amazon, and Salesforce have helped to define the web APIs we know and love today.

A commercial start

APIs were invented to change the way we do business on the web. This started a movement to make products and services available to customers via a single website. And developers started to automate the commerce that was powering the web. This period of time was dominated by three big players: eBay, Amazon, and Salesforce. These companies still continue to shape the world of APIs.Web APIs started to appear in the wild with the introduction of Salesforce on February 7th, when they officially launched their API at the IDG Demo 2000 conference. They introduced their enterprise-class, web-based, Salesforce automation as an “Internet as a service”, with XML APIs.Later on November 20th, 2020, eBay launched the eBay API along with the eBay Developers Program. These were originally only rolled out to a select number of partners and developers. Now it’s used for all goods sold on the web.Then on July 16th, 2002, Amazon launched its Amazon.com Web Service. This allowed developers to use Amazon.com content and features for their own websites. This way, third-party sites can search and display products from Amazon.com in an XML format.This development didn’t quite gain the momentum yet that we see today. Perhaps things weren’t quite ready. APIs only started to get traction when things got social.


The social web

In 2004, a new breed of API providers started to show up. This new group of providers changed how we use the web to share information with the people around us, both virtually and in the real world. These APIs weren’t directly linked to commercial value but they provided value to their organizations. They became lucrative platforms down the road.In 2003, Delicious, a new service for storing, sharing, and discovering web bookmarks emerged. It allowed people to view these bookmarks via a web interface. If you changed the extension from ‘.html’ to ‘.xml’ you would receive a machine-readable list of your bookmarks and developers took advantage of this. They built widgets and other embeddable features for social media.Then in 2004, Flickr was launched. They are a popular photo-sharing site. Six months after their official start, they launched their API. They became the image platform of choice for early blogging and social media movements because of their RESTful API. Users can easily embed their photos into blogs and social network streams.In 2006, Facebook launched its platform and API. This allowed developers to access Facebook users’ friends, events, photos, events, and profile information. It helped Facebook become one of the most popular social networks to date.One month later, Twitter introduced its own API in response to developers scraping content and data from the platform. Twitter incorporates APIs in almost every feature on the platform, from its mobile application to the share button.By 2010, social media had overtaken the population. APIs were intertwined in our personal lives and our professional lives. Facebook and Twitter dominated this API time period and they set the stage for a new generation of social influence powered by APIs. At the same time, Google also started to explore the power of web APIs. They launched the Google Maps API because many people were hacking the application.

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The Cloud

APIs were already being used for tons of commercial purposes. But Amazon really took APIs to the next level. It became the model for the next generation of companies. Amazon saw the potential of a RESTful approach and saw APIs in a way that nobody had seen before. This created a shift to focus on APIs across the whole organization. This means all shared resources were required to have an API. Eventually, this lead to the creation of two new Amazon Web Services.These web services are something completely different than the Amazon e-commerce site we know. The first web service was called Amazon S3. It provided a simple interface to retrieve any amount of data, at any time, from anywhere. It gives developers access to Amazon’s scalable, reliable, fast, and inexpensive data storage infrastructure.Shortly after that, Amazon launched its new cloud computing service called Amazon EC2. It provided resizable computing capacity in the cloud. This way, developers can launch different sizes of virtual servers within Amazon data centers.Cloud computing took web APIs to a higher level. This would impact our world in ways we could never have imagined.


While everyone was focused on social and the cloud, Apple launched the iPhone. This new device would prove to be a game-changer. It changed how we engaged with mobile phones and with the online world. Google responded to Apple by launching the open-source mobile platform, Android. This opened up a whole new world of possibilities that APIs would be the driving force of.Companies like Google Maps, Foursquare, Instagram, and Twilio stood at the forefront of this mobile API revolution. New APIs were made for these new mobile applications.This mobile evolution made web APIs what they are today. Mobile put the web in our pockets, enabling us to take photos, record videos, and share stories.We can learn a lot from the history of modern web APIs to keep revolutionizing APIs. APIs are also being used in cloud-connected devices like Fitbit, Google’s Nest, and Amazon’s Alexa.

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Different types of APIs

APIs can work differently depending on when and why they were created. That’s why there are many different types of APIs. Most APIs are web APIs. Here are four main types of web APIs:

Open APIs

These are open-source Application Programming Interfaces that you can access with the HTTP protocol. They are also known as public APIs with API endpoints and request and response formats.

Partner APIs

These are Application Programming Interfaces that are exposed to or by strategic business partners. Developers can access these APIs in self-service mode through public API developer portals. They must complete an onboarding process and get login credentials to access partner APIs.

Internal APIs or private APIs

These are Application Programming Interfaces that are hidden from external users. They are also known as private APIs because they aren’t available to users outside of the company. These APIs are intended to improve productivity and communication between different internal development teams.

Composite APIs

Composite APIs combine service APIs with multiple data. These APIs allow developers to access several endpoints in a single call. Composite APIs are useful in microservices architecture to gather information from several sources.

Different types of API protocols

Certain protocols have been developed to provide users with predefined rules that specify the accepted data types and commands. These different types of API protocols facilitate standardized data exchange:


SOAP stands for Simple Object Access Protocol. This means that the client and server exchange messages using XML. This API is not very flexible and was more popular in the past.


RPC stands for Remote Procedure Calls. The client completes a function and the server sends the output back. This protocol can use JSON and XML formats to transfer data.


REST stands for Representational State Transfer. It is a set of web API architecture principles and it has no official standards. These are the most flexible and popular APIs. The client sends requests to the server as data and the server uses this input to start internal functions. Eventually, it returns the output data back to the client. RESTful APIs can also be built with SOAP protocols, but the two standards are usually competing specifications.

Websocket APIs

Websockets APIs use JSON objects to pass data. They support two-way communication between client apps and the server. This is more efficient than REST APIs because the server can send callback messages to connected clients.

The difference between REST APIs and web APIs

Rest APIs are a special kind of web API that uses a standard architectural style. Modern web APIs are REST APIs. You can use these terms interchangeably.

API security

API security is the process of protecting APIs from cyberattacks. APIs enable access to sensitive software functions and data, which makes them a primary target for hackers. API security is critical when you develop a public API. SQL injection, broken authentication, Denial-of-service attack (DoS), and exposing sensitive data can be dangerous threats for APIs. Threats can use vulnerabilities in your API security to access your data. You can address these vulnerabilities by using best practices.

Why are API endpoints important?

Endpoints are the final touch points of the API communication system. This includes server URLs, services, and other specific digital locations that send and receive data between systems. API endpoints are critical to API security because they make the system vulnerable to attacks.

OWASP API security

The Open Web Application Security Project (OWASP) is a non-profit organization that releases a list of Web Application vulnerabilities every three to four years. This OWASP top 10 raises awareness about the most serious API security issues.

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Broken object-level authorization

Functions that accept user input and use it to access a data source can create level access control issues. This makes the attack surface bigger. You should carry out object-level authorization checks for these kinds of functions.

Broken user authentication

Hackers often exploit incorrectly applied authentication mechanisms. They can compromise an authentication token or exploit flaws in implementation to pause as another user. If APIs can't identify the user, it will compromise the overall API’s security.

Excessive data exposure

Data has to be filtered on the server-side. Developers often make the mistake of relying on the client-side to filter the data before displaying it to the user. This can create serious security issues. It's a good practice to deliver the relevant data to the client side.

Lack of resources and rate-limiting

No restrictions on the number or size of resources that the client can request can cause an impact on the performance of the API server. This can result in a Denial of Service (DoS) attack or it can expose authentication vulnerabilities that enable brute force attacks.

Broken function-level authorization

Overly complex access control policies and no clear separation between regular and administrative functions can result in authorization flaws. Hackers can exploit these vulnerabilities to gain unauthorized access to a user’s resources or perform administrative functions.

Mass assignment

The binding of client-provided data to a data model based on an allow list without proper filtering of properties can cause mass assignment. Hackers can modify object properties by exploring API endpoints, reading the documentation, guessing object properties, or providing additional properties through request payloads.

Security misconfiguration

Security misconfiguration can be the result of things like inadequate default, configurations, ad-hoc or incomplete configurations, misconfigured HTTP headers or inappropriate HTTP methods, and a lot more.


Injection flaws like SQL injection, NoSQL injection, and command injection involve data sent to an interpreter from an untrusted source via a command or query.

Improper asset management

APIs expose more endpoints than traditional web applications and thus they require structured up-to-date documentation. Exposed debug endpoints and deprecated API versions can widen the attack surface. Creating an inventory of deployed API versions and properly configured hosts can mitigate this problem.

Insufficient logging and monitoring

Hackers can take advantage of your insufficient logging and monitoring or your lacking incident response integration.

Best practices

Identifying vulnerabilities

To effectively secure APIs, you have to understand which parts of the API lifecycle are insecure. This isn’t always easy, especially if your organization has a large number of APIs. It’s impractical to consider all stages of the API lifecycle, from planning through development, testing, staging, and production.

Leveraging OAuth

Access control for authentication and authorization is one of the most important aspects of API security. A tool to control API access is OAuth, a token-based authentication framework. OAuth allows third-party services to access information without exposing user credentials.

Encrypting data

All data managed by an API, especially personal information or other sensitive data should be encrypted. This requires signatures to ensure that only authorized users can decrypt and modify data provided by your API.

Using rate-limiting and throttling

The more popular APIs become, the more valuable they become to attackers. APIs are a prime target for denial of service (DoS) attacks. It’s a good idea to set rate limits on the method and frequency of API calls to prevent these attacks. This protects against peak traffic that affects performance and security. It can also balance access and availability by regulating user connections.

Using a service mesh

Service mesh technology applies different layers of management and control when routing requests from one service to another. This optimizes the way these moving parts work together with correct authentication, access control, and other security measures.

Adopting a zero-trust philosophy

Insider threats are becoming more common and legitimate users often connect from outside the network perimeter. This makes everything more complicated. Zero-trust shifts the security focus from location to specific users, assets, and resources. It ensures that APIs always authenticate users and applications, provide privileges according to your role and monitor deviant behavior.

Testing your APIs

There are many ways to test your API security. You can test your application for vulnerabilities by using manual testing methods.

Jimber Solution

Web Application Isolation

Jimber works by applying a lot of these API security best practices to our solutions. The Jimber Web Application Isolation is an API security solution that uses zero-trust technology to protect your corporate applications using a container. Your data is interpreted in the container and only the graphical visualization of that data reaches the end-user. Attackers can only interact with the Jimber layer, but no longer directly with the APIs of the application. This way, any danger is gone.Our Web Application Isolation meets the highest demands and guarantees website security.

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The Jimber Web Application Isolation mitigates lots of the OWASP top ten 2021 vulnerabilities, by not exposing the APIs directly.Keep in mind that Jimber Web Application Isolation will function on top of your current security measures. It can’t stop every possible vulnerability on its own. However, it will strengthen any existing security measures taken and give a strong layer of extra protection.Learn more about our Web Application Isolation.Get more API security resources here: https://www.techtarget.com/searchapparchitecture/definition/API-securityOther topics that might interest you:The OWASP top ten 2021The ransomware attack: what it is and how it worksWhat is malware?

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