6 Infamous API Security Breaches: How to Safeguard Your APIs

The Essential API Security Checklist for Developers: A Comprehensive Guide

April 11, 2023

As modern software development adopts a more decentralized and interconnected approach, APIs (Application Programming Interfaces) have become essential for connecting different systems and applications. However, as APIs become more widespread, security vulnerabilities API adds to are becoming a genuine concern, making API security a critical challenge for developers. 

This article features a comprehensive guide for developers to ensure API security. We have included an API security checklist for designing secure APIs, including secure coding practices, testing for vulnerabilities, and API security best practices. 

Back to Basics: What is an API?

An API, or application programming interface, as the name suggests, is a set of protocols and tools that enable communication between different software applications. APIs define the methods for accessing and manipulating data and services within the application or system. As we move towards interconnected applications, it’s the APIs that connect various applications, services, and databases to provide a seamless and integrated user experience. 

When you order food on Doordash, several APIs, like the Google Maps API, get triggered in the backend to show you where the driver is. Additionally, there’s a payment API connected for payments. 

Importance of API security

APIs are the building blocks of many modern applications and systems, making them an attractive target for cyber attackers. Since APIs are open and at in many organizations unregulated, security breaches can expose host organizations’ sensitive data. 

Hackers exploit API vulnerabilities to gain unauthorized access to sensitive data or control the underlying system. Therefore, it is critical to ensure that developers heavily emphasize API security. 


Principles for Designing Secure APIs

Here are some principles followed by expert developers to instill API security:

Follow Best Practices for Designing Secure APIs

Developers can follow several best practices when designing secure APIs. Firstly, APIs should follow the principle of least privilege, where users have only the necessary permissions to perform tasks. Secondly, APIs should implement rate limiting to prevent brute-force attacks and ensure the system can handle high request volumes. Thirdly, developers should implement proper logging and auditing to track and detect suspicious activity.

Authentication and Authorization Techniques

Proper authentication and authorization mechanisms are essential to ensure that only authorized users can access APIs. To authenticate users, developers can implement various techniques, such as token-based authentication, OAuth, or JWT (JSON Web Tokens). Additionally, fine-grained authorization controls at object-level are necessary for APIs. Authorization techniques such as role-based or attribute-based access control are steps in the right direction to control user access to specific resources.  

Input validation and sanitization

Input validation and sanitization are crucial to prevent injection attacks such as SQL injection, command injection or cross-site scripting (XSS) attacks. Developers should implement strict input validation and sanitization to ensure user input does not contain malicious code or scripts. 

Error handling

Proper error handling is crucial to ensure that APIs do not expose sensitive information in error messages. Developers should implement error-handling mechanisms that do not reveal sensitive data and provide helpful error messages to users. 

Use of encryption and hashing

Encryption and hashing are essential for securing data at rest and in transit. Developers should use encryption to protect sensitive data, such as passwords or credit card information, both in storage and during transmission. Hashing ensures data integrity by converting plaintext data into a fixed-size hash, making it difficult for attackers to reverse engineer the original data. 

Testing for Vulnerabilities

Security testing is essential to API security, enabling developers to identify and remediate vulnerabilities. Security testing must occur at various stages of the development lifecycle, such as during development, unit-testing and integration-testing. Most importantly security testing shouldn’t be left to the last phase of the release cycle. 

Security Testing

Developers should perform various types of security testing, such as vulnerability scanning and penetration testing. Penetration testing involves simulating a real-world attack to identify vulnerabilities and assess the system’s resilience. Vulnerability scanning involves scanning the system for known vulnerabilities and misconfigurations. Code review deals with code inspection for security vulnerabilities. 

There are many tools available for security testing, both open-source and commercial. Organizations should include regular security testing tools as part of the development cycle. Ideally integrated with CI/CD pipeline where the security testing is part of every/daily builds.  

Techniques for remediation of security vulnerabilities

Remediating security vulnerabilities is essential to ensure that APIs are secure. To remediate vulnerabilities, developers can use patching, code refactoring, or configuration changes. Additionally, it is vital to perform continuous security testing to ensure that remediation efforts are functional. 

API Security Best Practices

Threat modeling

Threat modeling involves pinpointing potential threats and vulnerabilities and developing countermeasures to mitigate them. Developers should perform threat modeling at the beginning of the development lifecycle to identify and address security risks.

Risk assessment

Risk assessment involves evaluating the risks and determining the likelihood of an attack. Developers should perform risk assessments regularly to ensure the system is secure and identify any new risks that may emerge. 

Compliance with industry standards 

Compliance with industry standards such as PCI DSS or HIPAA is essential to ensure that APIs meet the required security standards. Developers should ensure that APIs adhere to industry standards and secure coding practices. 


Ensuring API security requires following best practices for designing secure APIs, secure coding practices, testing for vulnerabilities, and API security best practices such as threat modeling and compliance with industry standards.

APIs are essential components of modern software development and are becoming increasingly interconnected. Therefore, it is critical to follow best practices for API security to ensure that APIs are secure and do not pose a risk to the system or user data. 

Developers play a critical role in ensuring API security. The API security checklist presented in this article can help developers follow best practices and security standards to mitigate security risks during development.