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How do you level up DAST scans on your REST APIs?

February 6, 2023
Written by
Vishnu Prasad K

Table of Contents:

  1. Introduction
  2. Top 8 Free Tools for Automating REST API Testing
  3. Conclusion  


A DAST (Dynamic Application Security Testing) scanner examines a running application for vulnerabilities. It delivers automated alerts if it finds flaws that allow for attacks such as SQL injections, Cross-Site Scripting (XSS), and others. DAST tools can detect runtime issues since they are designed to perform in a dynamic context.

A REST API is an API that adheres to the REST (representational state transfer) architectural style's design principles. REST gives developers a great amount of flexibility and freedom. It's one of the reasons why REST APIs have become a popular way to connect components and applications in a microservices architecture.

So, if you are wondering how to level up your DAST scans on your REST APIs- we have the answer: Automate them!

Top 8 Free Tools for Automating REST API Testing

1. Rest Assured

REST Assured is a Java-based library that makes testing REST services in Java much more accessible. It is an open-source Java-based Domain-Specific Language (DSL) that allows you to write robust, readable, and maintainable automated tests for your RESTful APIs. REST Assured works particularly well with Maven, an automation tool used primarily for Java projects. 

It allows easy validation of technical response data and compilation of data-driven tests. Many RESTful APIs demand that consumers authenticate themself to interact with them. Widely used API authentication methods, such as Basic and OAuth 2.0 authentication, are supported by REST Assured.


  • REST Assured is a powerful tool for API testing because it eliminates the need for writing boilerplate code to set up an HTTP connection, send a request, and receive and parse a response. 
  • Additionally, its support for a Given/When/Then test notation makes tests human-readable.
  • Finally, since REST Assured is a Java library, it integrates easily into a continuous integration / continuous delivery setup, especially when combined with a Java testing framework like JUnit or TestNG.

2. Postman

Functional tests, integration tests, regression tests, and other types of tests can all be written using Postman. It can also be integrated with your CI/CD pipeline so that you can automatically test any code changes before they're deployed to production. This way, you can be confident that your API won't break in production.

Postman has tools for accelerating the API Lifecycle, including tools for design, testing, documentation, mocking, and discovery. It allows all your API artifacts to be conveniently stored, iterated upon, and collaborated upon on a single, shared platform across teams.


  1. Testers can quickly develop test suites by filling out templates using a simple interface. Postman also provides code snippets to help with script building, including examples of validations for response time, response code, etc.
  2. Postman users can easily access their files by logging into their account on a device with the Postman application or the Postman browser extension installed.
  3. Postman supports all HTTP methods, including storing progress, converting APIs to code, and changing the API development environment, among many more.
  4. Capabilities for tracking requests Postman supports different status codes for HTTP Responses to allow users to validate the response. 

3. Insomnia

Insomnia is a cross-platform framework for testing RESTful applications. Unlike Postman, Insomnia supports environment variables to reuse values across multiple requests. This open-source framework is powerful and easy to use, making it an excellent choice for any developer.


  • It's an open-source platform.
  • It's easy to create new plugins and template tags
  • SSL validation and client certificate assignment to workplaces
  • Generate code snippets in 12 different languages 
  • A detailed documentation section where instructions, code samples, and even test data can be supplied to specific methods or collections
  • With Insomnia, you can see HTML pages, images, SVGs, audio files, and even PDF Documents

4. Tavern

The Tavern is a Python library to perform automated tests on APIs with a simple & flexible YAML-based syntax. Using the Python library, you can also integrate Tavern into your own test framework or CI setup.


  • It's straightforward to use and highly customizable for challenging tests.
  • Both MQTT-based and RESTful APIs can be tested using Tavern.
  • Tavern functions as a Pytest plugin, requiring only the installation of Pytest and Tavern.
  • The Tavern can also be incorporated into your continuous test system integration.

5. Karate

Karate is an open-source solution that combines API test automation, mocks, performance testing, and UI automation in a single framework. Karate has a reputation for being easy to read & very maintainable.

It is possible to write tests without prior Java experience and support concurrent execution in several threads and configuration switching and staging. Users can write tests without necessarily being programmers.


  • Cucumber popularized the BDD syntax, which is language-neutral and straightforward enough for non-programmers.
  • There are built-in assertions and HTML reports, and you can run tests concurrently for performance.
  • There is also a cross-platform standalone executable for teams that need to become more familiar with Java.
  • It's not necessary to compile code. When writing tests, use a clear, concise syntax that has been carefully built for HTTP, JSON, GraphQL, and XML. Additionally, a single test script can combine API and UI test automation.
  • A Java API is now available for those who wish to programmatically integrate Karate's robust automation and data-assertion capabilities.

6. Hippie-swagger

API testing doesn't have to be a drag. With the Hippie-swagger tool, you can automatically validate your APIs against their Swagger documentation. By doing so, you can be confident that your requests and responses are always in sync and that your documentation is always accurate.


  • Maintains constant synchronization between the API documentation and the server and client
  • It enables us to communicate with the REST API and produce REST API documentation.
  • It responds to XML and JSON formats.
  • There are implementations for many technologies, including Scala, Java, and HTML5.

7. Frisby.js

Frisby.js is an excellent tool for testing API endpoints. It's flexible, easy to use, and fast. Plus, it has a bunch of built-in expect handlers to help you test the HTTP response of your API. 


  • With the help of several versatile tools provided by Frisby, it is now feasible to build end-to-end tests, and testing an entire REST API becomes enjoyable and straightforward.
  • Additionally, it allows you to define your unique handlers. For the most common things you need to test to ensure your REST API is functioning correctly and delivering the right attributes, values, and types, Frisby.js comes with many built-in tools.
  • When you require something specific, Frisby.js offers a simple approach to alter and expand assertions to simplify your task and produce less laborious and repetitive code.

8. Assertible

Assertible helps you automate your API testing as part of your CI/CD pipeline. It also lets you automatically sync your API tests with the latest specifications changes. Assertible is an API testing tool that continuously tests web services and focuses on automation and reliability.


  • It provides automation API tests through every stage of a continuous integration and delivery pipeline.
  • Support turn-key assertions for HTTP response validation, like JSON Schema validation and JSON Path data integrity checks
  • Users no longer need to manually update their tests after adding new parameters or changing the API response because the Sync feature allows them to do so when their specifications vary.
  • Encrypted variables, the newest feature from Assertible, offer a new way to store tokens, passwords, and secret data fields needed by tests to enhance API testing security procedures.
  • When you push code to GitHub or send alerts to Slack in the event of failures, Assertible integrates with the tools you already use to enable these actions.


DevSecOps is about securing software throughout the development lifecycle, from planning and designing to building, testing, and deploying. You're in luck if you want to learn more about DevSecOps' other components. AppSecEngineer offers a DevSecOp learning path that allows you to look into every minute detail related to this process.

We've got 7 courses that cover:

If you are looking to upskill or learn more about development workflow with automation, customization, and execution through GitHub Actions, perform comprehensive security tests on an application's source code (SAST) while it's running (DAST), and its open source components, sign-up with AppSecEngineer.

Source for article
Vishnu Prasad K

Vishnu Prasad K

Vishnu Prasad is a DevSecOps Lead at we45. A DevSecOps and Security Automation wizard, he has implemented security in DevOps for numerous Fortune 500 companies. Vishnu has experience in Continuous Integration and Continuous Delivery across various verticals, using tools like Jenkins, Selenium, Docker, and other DevOps tools. His role sees him automating SAST, DAST, and SCA security tools at every phase of the build pipeline. He commands knowledge of every major security tool out there, including ZAP, Burp, Findsecbugs, and npm audit, among many others. He's a tireless innovator, having Dockerized his entire security automation process for cross-platform support to build pipelines seamlessly. When AFK, he is either pouring over Investment journals or in the swimming pool.

Vishnu Prasad K


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