Your API Security Checklist for Building the Ideal API Security Strategy

April 30, 2024

Application Programming Interfaces (APIs) are critical for developing modern web services, mobile apps, and cloud computing. They enable seamless communication among various software applications, helping engineers create innovative products and services.

With the increased reliance on APIs, it is no surprise that they have become a prime target for cybercriminals, making API security a top priority that management cannot ignore. While recent statistics indicate that API-related security breaches are rising, current data suggests that relatively few organizations have implemented API security measures or have an effective API security strategy. 

This lack of coverage exists for several reasons, such as the misperception that Web Application Firewalls (WAFs) can secure APIs, inconsistency in API schema and functionality, lack of API endpoint visibility and inventory, or insufficient monitoring of the API attack surface.  A new breed of platforms dedicated to API security addresses these challenges and belongs in every application infrastructure serious about API security.

In this article, we will discuss the essential functionality covered by modern API security platforms that belong to a comprehensive API security checklist.

The ideal API security checklists

This table summarizes eight essential items your API security checklist must include: 

Checklist Item Description
Security testing Conduct regular security testing, including penetration testing and code reviews, to identify and fix vulnerabilities.
API documentation and versioning Create comprehensive and up-to-date documentation for API development and usage, as well as implement version controls to manage API changes.
Logging and monitoring Establish comprehensive logging and monitoring systems to detect and respond to security incidents.
Authentication and authorization Implement robust authentication mechanisms and authorization controls for APIs.
Data encryption Use robust encryption protocols to secure data transmission between clients and API servers.
Input validation Validate and sanitize input data to prevent common security vulnerabilities, like SQL injection.
Rate limiting Implement rate-limiting mechanisms to mitigate the risk of API abuse and potential DOS attacks.
Runtime protection Deploy solutions with runtime protection to actively shield APIs during operation, identifying and blocking malicious requests, data leaks, and other threats that traditional security measures might miss.

Seven elements of an API security checklist

In this section, we will go through each of the seven items of an API security checklist mentioned above in detail, providing a clear explanation and examples for each.

Security testing

Ensuring the security of your APIs is paramount in safeguarding your data and maintaining the trust of your users. A robust security testing strategy, including vulnerability assessment, penetration testing, and Static and Dynamic Application Security Testing (DAST), is essential to fortify your API against potential threats:

  • Conduct regular penetration testing: Periodically conduct penetration testing to simulate real-world attacks and identify potential vulnerabilities. This proactive approach helps uncover and address security weaknesses before malicious actors can exploit them.
  • Static Code Analysis with a security focus: Incorporate Static Application Security Testing (SAST) into your workflow. This will help analyze your code without executing it, uncover insecure coding practices and potential security vulnerabilities, and ensure adherence to established security standards.
  • Perform DAST: Integrate DAST into your security testing strategy to dynamically asses running applications. DAST interacts with the API endpoints in real time, mimicking user behavior to uncover vulnerabilities that may only manifest under specific conditions. This comprehensive approach enhances your ability to identify and mitigate security risks effectively.

Leveraging an API security platform that incorporates all these approaches simplifies API security testing and vulnerability management, which can be complex and time-consuming when done individually and manually. These platforms go beyond point-in-time assessment by seamlessly integrating with your development workflow, allowing developers to identify and fix security vulnerabilities within their code early in the development process. 

API documentation and versioning

API documentation is like a user manual for developers. Good documentation is essential to ensure proper usage and prevent unintentional security issues, contributing significantly to a secure ecosystem. This documentation should detail the purpose of each endpoint, the accepted parameters, and the expected responses.

As your APIs evolve, make sure to implement effective version control, which will help you manage changes while maintaining backward compatibility.

Here are some essential considerations:

  • Clearly define endpoints and resources: Provide clear and concise documentation for all API endpoints, detailing their purposes, accepted parameters, and expected responses.
  • Invest in an API security platform with automated discovery capabilities: Automatically discover your API assets, detect shadow, zombie, or outdated APIs, and generate API documentation.
  • Use Swagger or OpenAPI specifications: Consider using Swagger or OpenAPI specifications to provide machine-readable documentation that is easier to integrate with development tools and client libraries.
  • Update documentation regularly: Keep your documentation up to date with any changes to the API, including new features, modifications to existing endpoints, or changes to authentication requirements.
  • Deprecate older APIs: This is necessary to prevent potential security vulnerabilities.

Logging and monitoring

A comprehensive logging and monitoring system can be invaluable in ensuring the security of APIs. These systems provide a detailed overview of system activities and API interactions, detect anomalies, and identify unusual patterns, as well as enable a prompt response to security incidents.

These systems also play a vital role in maintaining compliance with industry regulations and standards, providing a detailed audit trail of all API interactions. 

Here are some relevant actions:

  • Log critical events: Implement logging for critical events, including authentication and authorization failures, errors, and unexpected behaviors. Capture relevant details such as timestamps, user identifiers, and the nature of each event.
  • Aggregate logs in centralized systems: Centralize logs in a dedicated logging system for easy management, searchability, and correlation of events.
  • Set up real-time monitoring: This monitoring should look at critical metrics such as API response times, error rates, and resource utilization.

Building and maintaining a complete logging and monitoring system is essential; however, managing separate tools and correlating different data can be challenging. This is where an API security platform that provides comprehensive API visibility and insightful monitoring can be very beneficial. These platforms centralize critical data, including authentication attempts, errors, and resource usage, providing a clear view of API activity and helping to identify and mitigate potential security risks.


Authentication and authorization

Authentication and authorization are two basic, yet important components that need to be part of every robust API security strategy. While these concepts are not new, and most developers and security practitioners are familiar with these two concepts, they are often not implemented or tested correctly. 

Authentication involves verifying the identity of users or systems trying to connect to your API. It prevents unauthorized access by requiring users to provide valid credentials, such as API keys, OAuth tokens, or other authentication mechanisms.

Authorization determines what actions an authenticated user or system is allowed to perform within the API. Role-based access control (RBAC) is a common authorization mechanism where users are assigned specific roles defining their permissions; for instance, an admin might have full access, while a regular user has read-only access.

In addition to following best practices for authentication, here are four practical steps to take to improve authentication and authorization implementation:

  • Implement multi-factor authentication (MFA): Enhance security by requiring users to further authenticate through methods other than a username/password combination, such as a one-time code sent to a mobile device or email address or an authenticator application.
  • Use token-based authentication: Implement OAuth or JWT (JSON Web Token) for secure and scalable authentication, reducing reliance on traditional username/password mechanisms.
  • Implement fine-grained permissions: Define specific permissions for different user roles, ensuring that users can access only the resources necessary for their tasks.
  • Regularly audit and update permissions: Conduct periodic reviews of user roles and permissions, removing unnecessary access and adapting to changes in organizational structure.
	"": {
		"Groups": [
			"All Users"
		"Roles": [
		"Permissions": [
			"Edit Account"

Example of a decoded JWT token showing defined roles and permissions

Data encryption

Data encryption is a must for API security. Encryption transforms data into a secure format that is unreadable to unauthorized parties, preventing access or interception of critical data during a data breach. 

Here are three essential steps you can take to safeguard your API data:

  • Enforce Transport Layer Security (TLS) for communication: Encrypt data in transit using TLS to ensure secure communication between clients and the API server.
  • Implement end-to-end encryption: Extend encryption beyond the communication channel to include end-to-end encryption, ensuring that data remains confidential from the sender to the recipient.
  • Encrypt data at rest: Protect stored data by encrypting it on the server. Utilize encryption mechanisms provided by the underlying storage system or database.

An illustration of encrypted communication between an API client and server

The illustration above shows the impact of implementing TLS by making the data unreadable to malicious actors who may intercept it, making it difficult for attackers to steal sensitive information such as passwords, credit card numbers, and other personal data.

By implementing these recommended action points, you can significantly improve the security of your API and safeguard against data breaches and unauthorized access to sensitive information.


Input validation

Attackers often exploit APIs that lack proper input validation, which allows them to inject malicious code. It is important to implement strong input validation or sanitization measures to prevent common vulnerabilities such as SQL injection, cross-site scripting (XSS), and other injection attacks. By validating and sanitizing user inputs, you can create a strong defense against malicious attempts to manipulate your API.

Here are some basic steps you can take to improve user input validation in your APIs:

  • Validate all user inputs: Scrutinize and validate all data received from users or external systems before processing it within the API.
  • Sanitize inputs to prevent code injection: Implement input sanitization methods to strip or escape special characters, preventing code injection attacks.
  • Use parameterized queries: Use these queries to stop SQL injection attacks when interacting with databases and ensure that user inputs are treated as data, not executable code.
  • Implement output encoding: Encode output data before rendering it in responses to prevent XSS attacks.

The following code snippet shows an example of input validation middleware using the express-validator library in a Node.js application with the Express framework:

const { body, validationResult } = require('express-validator');'/api/resource', [
], (req, res) => {
  const errors = validationResult(req);
  if (!errors.isEmpty()) {
    return res.status(400).json({ errors: errors.array() });

  // Process the sanitized input
  res.status(200).json({ success: true });

The code includes input validation middleware using express-validator to ensure that the “userInput” in the request body is a string, free of leading/trailing whitespaces, and escaped to prevent potential security issues. The server responds with a 400 status and error details if the input validation fails; if it succeeds, the sanitized input is processed, and the server replies with a 200 status response.

Rate limiting

Rate limiting protects your API from potential abuse and Denial-of-Service (DoS) attacks. With rate limiting, you can manage the number of requests that clients make to your API within a specific time frame. This helps prevent unauthorized access, performance degradation, DoS that leads to loss of availability, or other potential risks associated with excessive API usage and unrestricted resource consumption

Here are two basic steps extracted from a comprehensive guide to rate limiting to get you started:

  • Implement measures to limit the rate of requests made to the API and enforce these measures consistently.
  • Using an advanced API security platform can dynamically adjust the rate limits based on user behavior, traffic patterns, and resource usage with high confidence. An advanced platform should include behavioral analysis to differentiate between automated and human traffic to restrict abnormal behaviors.

While basic rate limiting provides essential protection, navigating its complexities and adapting to evolving threats can be challenging. An API security platform empowers you to implement sophisticated and dynamic rate-limiting strategies beyond static limits, offering features like adaptive throttling and behavioral analysis.

Runtime Protection

Runtime protection takes API security to the next level by safeguarding your APIs during operation, effectively shielding them from ever-evolving threats and vulnerabilities. It provides a dynamic defense mechanism that actively monitors and mitigates threats in real time. Unlike static security measures implemented during development, runtime protection operates during the execution of the API, continuously analyzing traffic and behavior to detect and respond to potential security threats. Beyond these capabilities, it offers several additional benefits, including:

  • Continuous monitoring: Runtime protection provides continuous API traffic and behavior monitoring, ensuring that security measures are always active and responsive. AI can provide smarter anomaly detection.
  • Dynamic adaptation: Unlike static security measures that may become obsolete over time, runtime protection adapts dynamically to evolving threats and attack techniques, maintaining robust security defenses and enforcement like rate limiting, blocking, deception, tarpits, and more.
  • Reduced time to detection and response: By detecting and mitigating threats in real time, runtime protection minimizes the time between detection and response, decreasing the potential impact of security incidents on API availability and integrity.

API security platforms like Impart Security have implemented a novel runtime protection feature that serves as an integrated API Firewall. In addition to analyzing requests and responses at runtime, identifying malicious API requests, and responding through blocking or behavioral rate limiting, this feature enables organizations to develop custom security rules for their APIs using coding concepts and a domain-specific language. As a result, security teams can easily tailor or expand their security policies to suit the requirements of complex API environments.



Securing your APIs is a crucial task that requires a proactive approach and constant attention. By following the eight items listed in this article’s API security checklist, you can strengthen your API security strategy and protect against possible threats.

It is important to note that performing a complete API security checklist is not a one-time situation—it is an ongoing process, and to ensure that your APIs are secure, you should perform a complete API security evaluation each time you update your build, release a patch, or modify your code. This will help you avoid creating new vulnerabilities when fixing old issues. Impart Security’s API security platform will help ensure that you can proactively analyze, mitigate, and respond to ongoing API threats.

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