What is an API? (Application Programming Interface)

What is an API?

API is the abbreviation for Application Programming Interface. But what does API mean? It is the mechanism that bridges the software components by enabling their communication. The API can also be referred to as a set of rules and procedures that state the method of communication. It is plugged into the existing systems to ease the transfer of information.

Watch the video below for an in-depth explanation of APIs!

What does API stand for?

Let’s understand what an API is and what it stands for with an example. You get information about the delivery route and location from the food delivery app whenever you order food. The food delivery app does not have a map system. Rather, it uses the data from Google Maps obtained through the Google Maps API to fetch location data and display routes.

Hence, to answer what does an API do here, the API enables communication between the food delivery app and Google Maps, providing up-to-date and required information. The API can also be used for numerous other services, such as weather updates, cloud computing services, payment processing, and social media integration.

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How do APIs Work?

The API works in a sequential process. Here is how it goes:

• The client or user (such as a mobile app or a web browser) sends a request through the APIs' Uniform Resource Identifier (URI)
• This request is sent forward to and processed by the server, which responds to the API
• Now, the API sends the server’s response back to the client in the standard format, such as data

The overall route of data transfer remains the same. However, different protocols or designs can be used to implement this flow. Based on how they are created and function, there are four main types of APIs:

SOAP APIs

SOAP stands for Simple Object Access Protocol; the messages are exchanged via XML. SOAP APIs were a preferred choice in the past but are less popular now due to their complexity, performance limitations, and other factors.

RPC APIs

RPC stands for Remote Procedure Calls. They enable developers to call remote functions on external servers, followed by the server sending back the output. These are suitable for situations like restarting a server remotely, using Machine Learning algorithms on the server to identify fraud, transferring money in a remote banking system, and others.

WebSocket APIs

These allow two-way communication between the client and server. Websocket APIs use JSON data format. They are based on the full-duplex and stateful protocol and use a 3-way handshake, with the latter being part of the TCP connection setup. 

REST APIs

These are widely used and flexible APIs with high use cases. Here, REST stands for Representational State Transfer (REST) architecture style. These are also referred to as RESTful APIs or RESTful web APIs. The REST APIs enable communication via HTTP requests to perform basic database operations on resources. They use standard request methods such as GET, PUT, POST, and DELETE.

Why is API Security Important?

Having understood what is an API and how it works, let’s proceed to its importance. The necessity of API security can be understood through the following points:

• API transfers critical data, and hence, a compromise can lead to the loss of confidential, sensitive, and financial data
• Exploitation of API by attackers can offer access to backend systems and their functionality
• API can be deemed unfunctional through Denial of Service (DoS) attacks due to inadequate rate-limiting
• Use of multiple internal APIs in microservices further enhances the risk of attack
• Rapid scaling may also lead to unmanaged or forgotten APIs
• Difference in the standards of API development can also lead to misconfiguration and insecure implementations
• It is even possible to inject or infect the secure APIs

Types of APIs

You know what is an API platform and its architectural types. But can it be categorized further? Yes, the APIs can be categorized based on usage as well. Now, based on this categorization, the different types of APIs are:

Private APIs: These are organization-specific and offer a connection of systems associated with the business. If you have ever wondered what is open API, this is the answer. The private APIs are open API.

Public APIs: These APIs are accessible to the public. These can be free of cost or paid and may differ in authorization requirements.

Partner APIs: Here, the API accessibility lies among the business partners. So, while they are externally available, there remains a limit.

Composite APIs: It involves a combination of two or more different APIs to carry out complex requirements.

What are API Integrations?

API integrations are the software components that enable communication between two applications through APIs. They allow data exchange between web-based tools and play a key role in developing cloud-based products. The API integrations serve multiple benefits, such as automating repetitive tasks, thus reducing manual load, decreasing the development time required to build every function from scratch, encouraging collaboration, and real-time data processing. They also offer secure access control and data protection.

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What are REST APIs?

REST APIs, or Representational State Transfer Application Program Interfaces, use specific functions to connect clients with data. The files are exchanged via HTTP and support a variety of data formats. REST APIs can be developed using any programming language. These are based on the following principles:

• Uniform Interface: The requests for a single resource must have a consistent structure, and the access should be done via a single and defined URI
• Client-server Decoupling: It involves the separate operation of client and server, with communication possible via standard requests and responses
• Cacheability: API responses must indicate their cacheability to increase scalability and performance
• Statelessness: The API request must comprise all the necessary information due to a lack of information storage on the server
• Layered System Architecture: The REST APIs will work across multiple layers, i.e., the intermediaries in the communication loop
• Code on Demand: These APIs are capable of returning the code if requested

What is a Web API?

Web API is an API that can be accessed over the web using the HTTP protocol. It can be developed using various technologies such as ASP.NET, Java, and others and is used in a web browser or a server. Web APIs are of four types: open, partner, internal, and composite API. Web APIs are mostly used with JavaScript, while multiple other methods remain available.

Web APIs are preferred for developing resource-oriented services, swift service development, devices with limited bandwidth, and lightweight and maintainable web services. The web APIs can be used to implement RESTFUL web services via the .NET framework, to develop ASP.NET applications via AJAX, and in other situations.

How to Create APIs?

Creating APIs is a simple task that takes a few steps. Here is how it goes:

• Define the requirement of the API and the target audience: The requirement involves specification of the type of information to be exchanged, the method of its presentation, and other relevant aspects
• Create the API architecture: Consider aspects like choice of programming language, usability, scalability, and security, and select between different API architectures such as SOAP, REST, and others
• Generate and implement the code: Generating the code will involve setting up endpoints, defining the methods, and including authentication
• Test the API and be updated on its working: Testing must be performed on parameters such as performance, security, functionality, and error handling 
• Improve with the help of feedback: Use the input to incorporate or enhance the features, fix bugs, enhance usability, and do more

Challenges of Using APIs

The challenges posed in handling APIs include: 

• Complex Integration Requirements: The problem generally arises from varying views on effective integration. Defining the perfect API integration requirements regarding data flow, speed, security protocols, performance expectations, functionality, and planning the overall procedure can help
• Challenging Onboarding: Incorporating the API may pose challenges to certain employees due to the requirement to deal with new complexities. Prior training by the experts and relevant knowledge can help with easy navigation
• Technical Ontegration Issues: Integration of the systems with the API can also cause workers to have certain technical problems. It also requires time and money to set up the API, depending on the application and the company’s existing systems. Carrying out the tasks in the presence of experienced individuals can make it less time and effort-consuming. Planning the finances can help in the financial aspect
• Compatibility Issues: The existing systems may not fit into the API due to the version differences, variety of data formats, and differences in API behavior. The integration with multiple platforms further adds to the challenges. Ensuring the compatibility would require additional work with careful consideration and thorough understanding
• Security Roadblocks: API integrations can pave the way for cyberattacks if done poorly or in insecure settings. For effective protection, real-time and continuous monitoring with upgraded security systems must be implemented

Advantages and Disadvantages of API

Proceeding further to learn about API, let’s understand the associated advantages and disadvantages.

So, beginning with the advantages of API, here we go:

• Support for a variety of programming languages allows convenient usage across different systems and improves performance for end users
• They exhibit cost efficiency by preventing the need to develop functionalities from scratch
• APIs from existing software systems can be reused, reducing time and effort
• API integration allows for the convenience of gaining real-time information, thus providing a better user experience for the audience
• Paves the way for a new source of income for the organizations by providing access to their systems
• While APIs may lead to security issues, the authentication and authorization policies offer significant protection
• APIs are scalable with the capability to handle numerous requests easily

Now, about the disadvantages, the list is as follows:

• API integrations connect the systems with the outside world and, hence, make them prone to attack
• APIs are pre-built, and hence, customization may be limited
• API integrations lead to dependence on third-party developers
• Implementation, maintenance, and management require time, effort, and individuals who have learned
• Integration may pose technical challenges and certain other complexities
• API may not be compatible with certain systems, compromising the functionality and leading to errors

Common API Security Threats

Some of the common API security threats that necessarily need to be considered for effective security are as follows:

1. Injection Attacks

It occurs when the attacker incorporates the API request with malicious data. The data enters the systems and begins executing unintended commands. It can also gain access to unauthorized data and may eventually lead to system compromise.

SQL, LDAP, and OS injections are common examples of this type of threat. The SQL injection attacks can be prevented by assessing the inputs, avoiding dynamic query execution, and using parameterized queries.

2. Broken Authentication

This attack occurs in the presence of improper authentication. Here, the attackers may again gain access to sensitive data or functionality. It can occur due to credential stuffing, the use of unvalidated tokens, the lack of verification of the request, the lack of validation of the expiration date, the non-encryption of the passwords, and other reasons.

Brute-force attacks and session hijacks are common examples here. Prevention is possible by implementing authentication mechanisms such as OAuth 2.0, preventing the exposure of credentials via URLs or logs, and including Multi-Factor Authentication (MFA).

3. Sensitive Data Exposure

These attacks are intentionally aimed at gaining access to data. Their entry point is to exploit vulnerabilities, involving unintentional exposure of sensitive data or in response to logs. The sensitive data here includes personal details, passwords, tokens, or other information. It may happen due to Broken Authentication, Object-Level Authorization, or Excessive Data Exposure.

Data encryption, strong access controls, data limitation in API responses, and avoiding including sensitive data in logs and URLs can prevent them. 

4. DoS and DDoS Attacks 

Denial of Service (DoS) and Distributed Denial of Service (DDoS) attacks are API attacks. The DoS attacks include an excessive number of API calls from a single source to the server, leaving it unable to respond to legitimate requests.

The DDoS attack involves multiple devices making numerous requests from various sources. Both threats are challenging to handle. Rate limiting, IP filtering, bot protection, and cloud-based DDoS mitigation solutions can prevent DoS and DDoS attacks.

5. Man-in-the-Middle Attacks

Here, the hacker attacks by intercepting the communication, requests, and messages. They get read-only access and modify the information. The hackers can also inject malicious code, leading to data breaches and unauthorized system access.

An example of a Man-in-the-Middle attack includes a fake WiFi hotspot and session hijacking. Preventing these attacks is possible through incorporating encryption methods like Transport Layer Security (TLS), using secure networks, and validating certificates.

6. API Spoofing

Spoofing refers to making the users believe that the communication or identity comes from an authorized source.

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Best Practices for Securing APIs

While certain challenges accompany API, they can be navigated through with a thoughtful approach and effective management. However, what is the API management practice to be followed? Enhancing the security of APIs is possible by following the best practices mentioned below:

• API Gateway Integration
• Incorporate the API behind a gateway to centralize traffic management features
• Secure Token Management
• Use JSON Web Tokens (JWTs) for access and refresh tokens
• Develop a standard JWT validation process as per the available libraries and specific to your needs
• Use a centralized OAuth authorization server to issue tokens
• Avoid forwarding the original access token; rather, use the token exchange
• Limit the access token permissions through OAuth scopes
• Access Control and Authentication
• Implement fine-grained access control at the API level
• Implement Role-Based Access Controls (RBAC) and keep the security documentation updated
• Keep the authentication methods of different strength levels separate to avoid privilege escalation
• Continuous Monitoring and Logging 
• Ensure continuous monitoring of the API by performing audits and logging information
• Network and Transport Security 
• Enforce HTTPS and TLS encryption for both internal and external APIs
• Incorporate zero-trust architecture
• Add an API firewall in two layers:
• Layer 1 (DMZ): For basic security checks
• Layer 2 (LAN): For advanced verification and deeper inspection
• Identity Management via IdPs
• Authorize and authenticate the APIs through third-party Identity Providers (IdP)
• Vulnerability Protection
• Secure against the Open Web Application Security Project (OWASP) top 10 vulnerabilities
• Stay updated on emerging threats and patch

Tools and Technologies for API Security

There are different types of API security tools, and their functionalities depend on their types. The insights into the same are:

1. API Linter Tools

They verify the API code and designs. These tools help improve missing rate limits, inconsistent naming, or insecure configurations, enabling the presence of clean and secure API standards.

2. API Mapping Tools

Also known as enumeration tools, these assist in identifying unprotected or unused endpoints, changes, and top-catch shadow APIs that may create backdoors for attackers.

3. API Gateways

They safeguard the traffic flow through authentication, routing, and rate limiting. They also work by restricting API access, blocking unauthorized access, and controlling the load.

4. Web Application Firewall (WAF) Tools

These tools impact protection from bot attacks and injection attempts. They work by checking incoming requests and blocking suspicious activity.

5. Dynamic Application Security Testing (DAST) Tools

These tools evaluate the endpoints to check for cross-site scripting, SQL injections, etc. They do so by sending requests to the live API.

6. Static Application Security Testing (SAST) Tools

These are responsible for assessing the codes at rest. These tools are used during API development.

7. Software Composition Analysis (SCA) Tools 

The SCA tools check the third-party dependencies in APIs and flag the known vulnerabilities. These tools scan the frameworks, packages, and libraries for potential issues.

Examples of common tools and technologies used in API Security are:

• Check Point CloudGuard WAF
• Burp Suite
• Imperva API Security
• CloudFlare API Gateway
• Akamai API Security
• Cequence Unified API Protection Platform

33% of financial services organizations and 50% of media/telecom organizations that are deriving revenue from APIs make more than $10 million through this channel. (Salesforce)

Real-World Case Studies

The real-world example of API adoption is as follows:

Boosting API Performance in a Leading Asia-Pacific Telecom Company

A leading telecom provider in the Asia-Pacific region faced performance issues while handling over 600 million monthly API calls across 800 internal APIs. Their existing cloud-based API infrastructure, optimized for external traffic, led to delays and was costly for internal API traffic.

The solution adopted by the company was to choose a real-time API management solution within their corporate network. It reduced latency by 70%, with API response times dropping to 20 ms or less. The new setup also empowered DevOps teams with self-service tools, streamlined CI/CD integration, and automated tasks, thus lowering operational workload.

API Integration to Enhance Healthcare Delivery

A regional hospital network used separate systems to store data, which led to delays in getting complete medical information. They handled the problem by connecting FHIR-based APIs with Electronic Health Records (EHR), medical devices, and telehealth tools in real-time.

The consequence was that the doctors and staff could access patient records 60% faster and work more smoothly across departments. The API setup also made it easier to follow the rules and offer better telehealth services.

Scaling Financial Transactions Through Unified API Management

A financial services firm needed a cost-effective, high-speed solution to process billions of API calls across REST, SOAP, and external services. The previous system involved three separate tools, leading to redundant configurations and limited scalability. The firm adopted an open-source, event-driven API infrastructure to improve API management.

It helped consolidate systems and supported 360 billion monthly API calls with 2 million peak calls per second. The company also incorporated Lua-based modules that allowed real-time upgrades without downtime, enhancing performance and reliability. It enabled DevOps teams to receive high throughput for internal and partner applications.

API vs Webhooks vs SDKs

The comparison of API, Webhook, and SDK can be done as follows:

Conclusion

So, to help you recall what an API is and what API stands for, it is defined as a mechanism that allows the application or service access to a resource within the service, application, or database. APIs simplify development, improve connectivity, and contribute to a better user experience. However, with enhanced usage comes the risks of exploitation of vulnerabilities, injection of attacks, and others. Proper security measures need to be taken to ensure efficient security.

Including API security tools and technologies can help in the endeavor. Further, beforehand preparation and including best practices while implementing and maintaining the API help navigate challenges effectively. The API integration has also exhibited effective results in real-world use cases.

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FAQs

1. What is an API with an example?

API is the medium that allows software to communicate using a set of definitions and protocols. A common example of API communication is a phone's weather update.

2. Why do we use APIs?

APIs allow real-time communication and information updates through interaction with software systems or servers. They ease the development of software programs by allowing developers to reuse existing functionalities instead of building everything from scratch.

3. What are the four types of APIs?

The four types of APIs based on their usage are public, private, partner, and composite APIs.

4. What language are APIs written in?

APIs can be written in any programming language. However, the commonly used ones include Python, Java, JavaScript, Ruby, and others.

5. Which API is most popular?

REST API is a widely used and popular type of API due to its high scalability, flexibility, and simplicity. It is also easy to maintain, integrate, and lightweight, enhancing its preference.