What are API Calls and How to Make Them?

API Calls

APIs are the lifeblood of today’s online apps and services, but they’re also one of the most common attack vectors for malicious hackers. Even if you don’t realize it, API calls are an integral part of your daily digital interactions, whether you’re using a smartphone app, browsing a website, or accessing cloud services. If you’ve ever requested information from a website using its search bar, then you’ve made an API call! This article is your comprehensive guide to the world of API calls, exploring their significance, how to make them, and the crucial aspects of securing them.

What Is An API Call?

At its essence, an API call is a request made by one software component or application to another, soliciting specific data or functionality.

These calls predominantly employ HTTP requests and can range from straightforward tasks like retrieving weather data to intricate processes such as, if you want to see what your current balance is in your bank account, then this would be an API call because it requests information from the server.

This is different from an RPC call, which would be more like asking the server to make a change on your behalf. For example, if you wanted to transfer money from one account to another, then this would be a request for an RPC call.

Making Multiple Calls At Once

While a single API call may seem straightforward, real-world applications often necessitate the execution of multiple calls to various APIs or endpoints in parallel to accomplish complex tasks efficiently. These scenarios might involve amalgamating data from diverse sources, coordinating intricate workflows, or optimizing performance. Developers adeptly employ techniques such as batching, parallelism, and asynchronous processing to manage multiple API calls concurrently, ensuring that applications remain responsive and perform optimally even under heavy loads.

When you want to make multiple API calls at once, it’s important to understand how each method works. The methods available are:

  • POST – This method allows you to send multiple pieces of data at once without having to create separate URLs for each piece of information being sent through your website or app interface.
  • PUT – This method allows users who have permission access rights on an endpoint (like Twitter) to upload files up until their file size limit before beginning processing.
  • HTTP Request Header – The most common method is to use an HTTP request header. This allows you to send multiple variables at once, even if they’re not all on the same page or website.
  • GET – This method is used by search engines and browsers to retrieve data from your website or app. It’s also the most common method of sending data through HTTP requests, but it’s not suitable for sending large amounts of data.

How To Make API Calls?

To make API calls effectively, developers must adhere to specific protocols and employ the requisite tools and libraries. Here’s a step-by-step breakdown of the key processes involved in making API calls:

Choosing the API

Select the API(s) that align with the functionality or data you require, taking into account factors like reliability, data coverage, and scalability.


Many APIs mandate authentication to ensure secure access. Developers must obtain API keys, tokens, or credentials from the respective service provider to establish their identity and entitlement to access the API.

Constructing the Request

Construct a structured HTTP request, specifying essential parameters such as headers, query parameters, and the request body, to articulate the desired action and the data needed.

Sending the Request

Utilize programming languages and libraries compatible with your chosen API to dispatch the HTTP request to the designated API endpoint. Widely embraced options include Python’s requests library, JavaScript’s fetch API, and specialized SDKs offered by API providers.

Handling the Response

Upon receiving the response from the API, typically formatted in JSON or XML, developers parse and extract the pertinent data or information required for further processing within the application.

API Calls Used For An Attack

API calls can be used for malicious purposes. They can be used to steal data, make money, disrupt operations, and cause damage. Attackers may exploit APIs through various means, including unauthorized API calls, distributed denial-of-service (DDoS) attacks, or identifying vulnerabilities within the API implementation. Protecting your APIs from such malicious activities is pivotal to ensuring the security of your applications and data.

Common attack vectors concerning API calls encompass:

  • API Key Theft: Attackers may endeavor to pilfer API keys or tokens, which if successful, could grant them unauthorized access to the API. Vigilant key management practices are indispensable to thwart such theft attempts.
  • SQL Injection: Insufficiently sanitized input data could expose APIs to SQL injection attacks, where attackers manipulate API requests to execute unauthorized SQL queries on your database.
  • Denial of Service (DoS) and Distributed Denial of Service (DDoS) Attacks: Malicious actors may flood your API with an overwhelming volume of requests, impeding its functionality and causing service disruptions for legitimate users.
  • API Rate Limiting Bypass: Crafty malefactors might attempt to circumvent rate limits by employing multiple IP addresses or user accounts to generate an excessive number of API calls, potentially overloading your infrastructure.
  • Flooding Servers: API calls are also used in attacks on servers. The attacker will send a flood of requests to the server to try and overload it with work so they can’t respond properly or even crash the server altogether.

To fortify your APIs against such vulnerabilities and threats, it’s imperative to implement an array of security measures.

Why Use An API Call?

API calls extend their utility beyond developers alone; they offer a multitude of advantages to various stakeholders across diverse domains. You can also use API calls to automate tasks that involve pulling information from different websites:

Enhanced Functionality

APIs empower developers to augment their applications’ capabilities by seamlessly integrating external services, enabling features such as geolocation, social media sharing, and secure payment processing.

Data Access

API calls serve as gateways to valuable data from external sources, facilitating informed decision-making. Accessible data spans a wide spectrum, including real-time weather updates, financial market data, and insights from social media platforms.


APIs underpin automation across numerous domains, streamlining repetitive tasks and workflows, mitigating errors, and bolstering operational efficiency.

Third-Party Integrations

API calls facilitate frictionless integrations with third-party services, fostering collaboration and interoperability within the sprawling digital ecosystem. These integrations are pivotal in domains like e-commerce, where seamless payment gateways are critical.

Securing APIs From Invalid API Calls

The security of your APIs is paramount to safeguard your data, preserve your organizational reputation, and ensure a seamless user experience. Here’s an in-depth look at best practices for securing your APIs against invalid or malicious API calls:

Authentication and Authorization

Implement robust authentication and authorization mechanisms to ascertain that only authenticated, authorized users, and applications can access your APIs. Employ tokens, API keys, OAuth, or JSON Web Tokens (JWT) to establish secure authentication workflows.

Rate Limiting

Enforce rate-limiting policies to restrict the volume of API calls a user or application can make within predefined time intervals. This proactive measure deters potential DDoS attacks and prevents the abuse of your API resources.

Input Validation

Adopt stringent input validation processes to sanitize and validate incoming data, thwarting injection attacks such as SQL injection and Cross-Site Scripting (XSS). A robust input validation strategy safeguards your API against malicious payloads.

HTTPS Encryption

Mandatory implementation of HTTPS encryption ensures that data transmitted between clients and your API server remains confidential and tamper-proof, mitigating the risk of eavesdropping and data manipulation during transit.

API Key Management

Implement rigorous API key and token management practices, including periodic rotation, to minimize the risk of unauthorized access. Effective management significantly enhances the security posture of your API infrastructure.

Monitoring and Logging

Establish comprehensive monitoring and logging capabilities that continuously scrutinize API traffic for irregularities and potential security breaches. Employ specialized tools and services that facilitate in-depth analysis and real-time response to suspicious activities.

API Documentation

Maintain exhaustive API documentation that includes comprehensive security guidelines for developers and consumers of your API. Encourage adherence to best practices and security protocols to foster a security-conscious developer community.


As you embark on your journey into the realm of API calls, bear in mind that a well-designed and secure API can be a transformative asset for your organization. By adhering to industry best practices, understanding the intricacies of API calls, and remaining vigilant against potential threats, you can harness the true potential of APIs while safeguarding your systems and data. In this article, we took a look at what an API call is, how it works, and some examples of how you can use it. If you’re looking for more information on APIs or other programming topics, check out our other articles!

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