Connecting digital services and transferring data, APIs are critical for any modern technology business. But securing them has proven to be a challenge for developers and security managers alike, with many high-profile security incidents in recent years. According to Gartner, 90% of web-enabled applications already have a larger surface area in exposed APIs than in the user interface. 

In this article we’ll look at the most common API security risks and vulnerabilities, how to test for them with the right API penetration testing tools, and how to choose the best API security tool to protect your APIs – wherever you are in your CI/CD pipeline.  

What can go wrong with APIs? 

API breaches have the potential to expose large amounts of sensitive data or give attackers access to your systems. But where do you start? Firstly, you should focus your security efforts on the most common vulnerabilities listed in OWASP’s API Security Top 10.  

These include broken authentication, misconfigurations and injection attacks, all of which can lead to serious breaches and data disclosure, like when Freepik fell victim to a SQL injection blunder that compromised the accounts of 8.3 million users in 2021. Want to know more? Deep dive into these vulnerabilities and more in our ultimate guide to API security.

How can you secure your APIs? 

Similar to web application security, API security testing tools send a variety of requests designed to safely mimic attacks of would-be hackers to produce a report listing any vulnerabilities or bugs. API security testing aims to ensure that API security vulnerabilities like the ones above have been identified and fixed prior to releasing or changing your API. 

Best API security testing tools 

It’s important to choose an API security testing tool that fits your needs as a developer, penetration tester or security team. It should also help you identify or defend against as much of the OWASP Top 10 as possible, and work with your current tech stack to continuously monitor your APIs from current and emerging threats. What’s safe today may not be safe tomorrow. Now you know what to test for and why it’s important, here’s our list of recommended API security tools to cover a variety of scenarios: 

Best API security tools for DevSecOps 

Intruder 

Designed with simplicity in mind, Intruder’s fully informed API security scanning runs comprehensive scans against every endpoint listed in an API schema, helping customers looking to secure APIs with Single Page Applications (SPAs) who struggle to get meaningful results from traditional application vulnerability scanning. Its Dynamic Application Security Testing (DAST) scanner is easy to integrate into your CI/CD pipeline to find so you can resolve issues early in the DevOps lifecycle. Get a feel for our API scanning tool and how easy it is to run API security scans with our interactive demo below.

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Probely 

Probely is designed to integrate into software development processes and CI/CD pipelines to automate and scale security testing. Its automated web app vulnerability scanner has fully featured API scanning capabilities to help detect vulnerabilities and provide actionable advice on how to fix them. But beware, as with Burp Suite, its free plan has limited functionality. 

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AppCheck 

As its name suggests, AppCheck provides in-depth automated testing that allows ad-hoc, scheduled and continuous API security testing, including full OWASP Top 10 vulnerability coverage. Developed and maintained by security experts, it’s easy to use and highly configurable, supporting all forms of authentication via a scriptable browser interface and integration with bug tracking platforms like JIRA, and custom integration via JSON API.

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Best API security tools for enterprise

Firetail 

A more recent entrant to the market with an enterprise focus is Firetail, whose mission is to provide a single API security platform for application layer visibility and real-time, inline inspection and blocking of malicious API calls. Flexible and configurable, users can define triggers to generate push notifications which leverage configuration and inventory data. It also integrates with notification systems from email to Slack and Teams. 

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Best for pentesters and bug bounty hunters 

Burp Suite 

Burp Suite is a comprehensive set of testing tools developed for pentesting and running API security scans for vulnerabilities. An all-in-one tool that supports a multitude of ways to inspect, modify, and replay HTTP requests, it’s popular among developers, web app security researchers, engineering teams and bug bounty hunters. It’s easy to use compared to other tools, although the free ‘community edition’ has significantly limited functionality.  

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Best for developers

Postman 

Postman is used by pentesters and developers worldwide to allow QA and Application Support teams to make it easier to test APIs. The GUI is straightforward and user friendly and their API platform can check for vulnerabilities beyond the OWASP API Top 10. This provides clear security guidelines to developers on the same platform that they use to design, build, test, and deploy their APIs. However, it can add headers to a request, regardless of your authorization, and this can lead to an error response from backend APIs. 

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Best for post-deployment

Cloudflare 

Cloudflare is a suite of solutions designed to make everything you connect to the internet secure, private, fast, and reliable. Designed for pros and newbies alike, its API Gateway discovers and monitors API endpoints to prevent application DDoS and brute-force attempts, provide authentication, and validate OpenAPI schemas. It stops volumetric API abuse through anomaly detection, prevents data leaks by continuously scanning response payloads for sensitive data, and provides a central API catalogue for a single baseline of organizational APIs. 

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Why you need to take API security seriously

APIs are a critical part of most mobile and web applications. Knowing where your APIs are, and understanding how attackers can exploit them, is more important than ever. Frequent API security scans help to secure your application by identifying weaknesses so you can fix them before they're exploited. 

Intruder's dynamic application security testing (DAST) scanner scales API vulnerability scanning to meet the needs of your growing business. Read more in our guide to API security or find out more about our approach to API scanning here. Why not put Intruder through its paces with a free trial? 

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