API Testing in CI/CD: Tools Comparison
API testing is essential for ensuring your software works reliably, especially in CI/CD pipelines. It helps catch bugs early, improves performance, and ensures secure, functional APIs. This article compares five popular tools for API testing: Katalon Studio, Postman, ReadyAPI, JMeter, and REST-assured.
Key Takeaways:
- Katalon Studio: Low-code, supports REST, SOAP, and GraphQL. Best for teams needing a mix of codeless and script-based testing. Paid plans start at $183/user/month.
- Postman: User-friendly with collaboration tools. Ideal for REST API testing. Free plan available; premium plans start at $14/user/month.
- ReadyAPI: Comprehensive testing for REST and SOAP APIs. Great for enterprise needs but expensive for small teams.
- JMeter: Open-source, excellent for performance testing and load testing. Requires Java expertise.
- REST-assured: Open-source Java library, perfect for developers comfortable with Java. No GUI; focuses on code-driven testing.
Quick Comparison:
| Tool | Supported Protocols | Key Features | Cost |
|---|---|---|---|
| Katalon | REST, SOAP, GraphQL | Low-code, data-driven testing | From $183/user/month |
| Postman | REST | Intuitive, mock servers, collaboration | Free to $49/user/month |
| ReadyAPI | REST, SOAP, JMS, JDBC | Unified testing, enterprise focus | Expensive for small teams |
| JMeter | HTTP, REST, SOAP, GraphQL | Open-source, load testing | Free |
| REST-assured | REST | Java-based, BDD syntax | Free |
Each tool has its strengths and limitations. Choose based on your team’s technical skills, budget, and testing needs. For Java-heavy teams, REST-assured is a great fit, while Postman suits teams looking for ease of use. Dive into the full article for detailed insights on each tool.
Top 5 API Testing Tools for REST & GraphQL in 2025
1. Katalon Studio
Katalon Studio has earned the trust of over 65,000 enterprises and teams, including well-known names like FPT Software, Sony, Panasonic, and BBVA. With a global user base exceeding 1 million, it’s a go-to platform for both script-based and codeless testing.
Integration with CI/CD
The Katalon Runtime Engine (KRE) plays a key role in integrating Katalon Studio with CI/CD pipelines. Acting as a command-line interface (CLI) agent, it facilitates automated test execution within pipelines and simplifies setup with built-in compatibility for leading CI/CD tools.
"Katalon Runtime Engine (KRE) is a CLI-based agent for executing Katalon Studio tests in CI/CD pipelines, enabling scalable and parallel test execution." – SoftwareOne Marketplace
Katalon Studio works seamlessly with major CI/CD platforms, offering official integration with tools like Azure DevOps, Docker-configured GitLab pipelines, and GitHub Actions. Its CLI-based runtime engine ensures smooth execution while supporting flexible protocols, making it a reliable option for continuous testing.
Supported Protocols
The platform supports multiple API protocols, including REST, SOAP, and GraphQL APIs, giving teams the versatility they need for modern testing requirements. It also allows importing tests from popular sources like Swagger, Postman, and WSDL files. This feature not only saves time during setup but also lets teams leverage their existing test assets effectively.
Automation Features
Katalon Studio goes beyond basic automation by offering data-driven testing, which links test cases to external data sources such as Excel or CSV files. This approach covers a wide range of scenarios with minimal manual effort. Additionally, its parallel test execution feature helps organizations optimize resource use, especially when dealing with large test suites.
Detailed test reports generated by the platform provide valuable insights into API performance and identify areas for improvement.
"Testing with Katalon Studio is truly easy to set up – say goodbye to cruel settings… it provides out the box integrations with other CI tools (Jenkins) to support our CI testing goal." – QA Executive
Katalon Studio also supports integration with version control systems like Git, making collaboration on test scripts seamless. Features like custom keywords and command-line execution further streamline repetitive tasks, boosting efficiency.
Cost/Scalability
Katalon Studio offers pricing plans tailored to different team sizes and needs.
- The Free Plan includes 2,000 monthly test results, supports up to 5 users, one organization, and three active projects.
- The Premium Plan, starting at $25 per month (billed annually at $299), increases the limit to 3,500 monthly test results, allows unlimited users, and supports up to 10 active projects.
- For larger teams, the Enterprise Plan provides unlimited users, organizations, and active projects, along with 30,000 monthly test results.
Additional components include Katalon Studio Enterprise at $2,099 per user per year (or $175 monthly, billed annually) and Katalon Runtime Engine at $1,679 per concurrent session per year (or $140 monthly, billed annually).
While many teams find the platform scales well for small to mid-sized setups, its transition from a free tool to a subscription-based model has prompted some to assess whether the pricing aligns with their specific needs.
2. Postman
Postman continues to be a go-to tool for API testing in CI/CD pipelines, combining user-friendly features with powerful automation tools. It’s a trusted platform for API development and testing, with millions of developers incorporating it into their workflows.
Integration with CI/CD
Postman seamlessly integrates with popular CI/CD tools like Azure Pipelines, CircleCI, GitHub Actions, GitLab CI/CD, Jenkins, and Travis CI, using its CLI to automate API tests whenever new code is pushed to a repository. This integration ensures that API tests are triggered automatically, with detailed feedback provided through the command line. For enterprise users, Postman also includes API Governance and Security checks, making it a reliable choice for teams managing complex workflows.
Automation Features
Postman simplifies the process of creating and running automated tests. Using the Collection Runner, developers can sequence API requests and apply environment variables to test different configurations. It also allows teams to combine multiple tests and requests into a single automated sequence, streamlining the testing process. For added efficiency, Postman includes a code snippet library to help developers write tests for each request in a collection, while parallel test execution ensures faster processing. By supporting shift-left testing, Postman automatically runs tests in CI/CD pipelines as soon as new code is pushed, helping developers catch issues early and maintain code quality.
Cost/Scalability
Postman offers flexible pricing plans to suit various team sizes and needs:
| Plan | Monthly Price | Annual Price | Features |
|---|---|---|---|
| Free | $0 | $0 | Up to 3 collaborators |
| Basic | $19/user | $14/user | Enhanced collaboration features |
| Professional | $39/user | $29/user | Advanced testing capabilities |
| Enterprise | Contact Sales | $49/user | Organization-wide API development |
For scalability, Postman provides pay-as-you-go options for mock server requests and monitoring. Additional mock server requests and monitoring cost $20 per 50,000 requests per month. Teams requiring comprehensive API test automation can add $49 per user per month to their Enterprise Essentials plan.
User feedback highlights Postman’s reliability, speed, and overall stability, earning it a 4.7 out of 5 rating from 498 reviews. However, some users have suggested enhancements in API design tools and OAuth2 support to further improve its value.
3. ReadyAPI
ReadyAPI is a low-code API testing platform that brings together functional, security, and performance testing into one solution. Evolving from tools like SoapUI Pro, LoadUI Pro, and ServiceV Pro, it simplifies API testing workflows, particularly in CI/CD pipelines.
Integration with CI/CD
ReadyAPI makes it easy to incorporate API tests into automated build processes, thanks to its plugins and the TestEngine component. It offers native plugins for widely-used CI tools like Jenkins, Maven, TeamCity, and Azure DevOps. Whether you’re running tests locally, in Docker containers, or across distributed staging environments, ReadyAPI adapts to various deployment needs, aligning with the fast-paced demands of modern development.
"ReadyAPI is one of the best tools for API testing because they have made a single platform for functional testing, load testing security, and also service actualization. For integration for CACD, they have something called TestEngine, which can also be an add-on for ReadyAPI."
– Vallalarasu P., Test Architect at a tech services company
By integrating API tests into the build process, ReadyAPI helps teams identify issues early, reducing the complexity and cost of fixing bugs later in the development cycle. This seamless integration lays the groundwork for its broad protocol capabilities.
Supported Protocols
ReadyAPI supports a wide range of protocols, making it a versatile choice for testing diverse API systems all within one platform. It handles modern protocols like REST, SOAP, and GraphQL, which cover most API testing needs. For enterprise-level requirements, it also supports JMS (Java Message Service) and JDBC (Java Database Connectivity), enabling teams to test databases and messaging systems alongside APIs. Additionally, it works with messaging protocols such as Kafka, AMQP, and MQTT, as well as older protocols like HTTP/HTTPS, FTP, and XML-RPC, ensuring compatibility with legacy systems. This extensive protocol support enhances ReadyAPI’s automation capabilities.
Automation Features
The platform’s automation features are designed to minimize manual work while ensuring thorough test coverage. It supports data-driven testing with inputs from spreadsheets, databases, or CSV files. ReadyAPI also allows the reuse of test case templates, which is a major advantage as test suites grow more complex. For automated workflows, it offers command-line execution, enabling seamless integration into build pipelines. It even handles intricate scenarios, such as logging in and using the resulting authentication data to test enterprise messaging services – all within a single test case.
Cost/Scalability
ReadyAPI uses a commercial licensing model, with pricing tailored to team size and feature needs. It offers various tiers to accommodate everyone from solo developers to large enterprise teams. Beyond licensing, ReadyAPI promotes collaboration by allowing teams to share projects, artifacts, and even licenses among members. It also lets users log issues directly from the testing IDE, streamlining workflows.
"It also aids in faster feedback to developers, allowing them to implement developments in a sprint without the need for extensive testing afterwards, thus improving our time to market metrics."
– Walter Wirch, Technical Expert at Bertelsmann SE & Co.
For teams integrating ReadyAPI into their CI/CD pipelines, its ability to operate in distributed environments ensures that testing infrastructure can scale horizontally as API portfolios grow. This flexibility removes the bottlenecks of single-machine limitations, making it a robust solution for growing organizations.
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4. JMeter
Apache JMeter is a widely-used open-source tool designed for performance testing. While it originally focused on web applications, it has evolved to support comprehensive API testing across various protocols. Its affordability and flexibility make it an excellent choice for teams aiming to incorporate performance testing into their CI/CD workflows.
Integration with CI/CD
JMeter works smoothly with popular CI/CD tools like Jenkins, GitLab CI, and Travis CI, enabling teams to automate performance testing. By storing JMeter test plans in version control systems like Git, teams can configure CI/CD pipelines to trigger tests automatically – whether on code commits or scheduled builds. Running JMeter in non-GUI mode ensures efficient resource usage, making it ideal for automated environments.
For example, Jenkins Pipelines allow teams to execute JMeter tests across different environments – development, staging, and production – with minimal manual effort. This seamless integration ensures continuous performance monitoring and faster feedback loops.
"Integrating Apache JMeter into your CI/CD pipeline empowers your team to deliver high-performance software. By the automation phase of performance testing, configuring seamless integrations with tools like Jenkins, and enabling scalability testing, you ensure faster feedback, proactive performance monitoring, and efficient resource utilization."
– Rupesh Garg, Founder and Principal Architect at Frugal Testing
A real-world example underscores JMeter’s value: an e-commerce development team implemented JMeter in their CI/CD pipeline from the first sprint. Automated tests caught a memory leak in the shopping cart service early on. Later, during staging tests, the pipeline flagged a database bottleneck that could have caused crashes under peak traffic.
Supported Protocols
JMeter’s versatility extends to its support for a wide array of protocols, making it a strong choice for modern API testing. It handles HTTP, HTTPS, REST, SOAP, and GraphQL, covering most contemporary API testing needs. For enterprise-level testing, it also supports JDBC for database interactions and JMS for messaging systems. Additional protocols include FTP, LDAP, SMTP, POP3, IMAP, and TCP.
This focus on API responses rather than full browser behavior ensures efficient testing. JMeter also supports multiple authentication methods – like basic authentication, OAuth, and custom implementations – allowing for comprehensive testing of secured APIs.
Automation Features
JMeter simplifies testing with features like modular test plans and parameter substitution, which reduce the need for separate configurations across environments. Reusable test components can adapt to different deployment stages through parameterized settings.
Teams can programmatically configure headers, request bodies, and authentication options. Scheduled test executions – whether nightly or weekly – further streamline workflows. For more complex scenarios, JMeter can simulate realistic user journeys, providing insights into how APIs perform under real-world conditions. This helps uncover bottlenecks that artificial loads might miss.
Cost and Scalability
As an open-source tool, JMeter eliminates licensing costs, making it an affordable alternative to commercial performance testing solutions. The main investments involve infrastructure for distributed testing and the time required to develop test scripts and analyze results.
JMeter’s distributed testing capabilities allow teams to simulate thousands of concurrent users using cloud platforms like AWS or Azure. Running JMeter in non-GUI mode minimizes resource usage, while cloud-based infrastructure offers virtually unlimited scalability. This combination of cost savings and flexibility makes JMeter a practical choice for organizations with diverse API testing demands.
"JMeter helps you identify performance bottlenecks and evaluate how your application behaves under stress. For testing a web server’s response times or the scalability of API tests, JMeter makes it easy to gather essential data and improve your application’s performance."
– Rupesh Garg, Founder and Principal Architect at Frugal Testing
5. REST-assured
REST-assured is an open-source Java library designed to make API testing more straightforward, especially for teams working within Java ecosystems. By using a domain-specific language (DSL) and Behavior-Driven Development (BDD) syntax, it allows testers to write clear, maintainable API tests. Unlike GUI-based tools, REST-assured focuses on code-driven testing, making it a natural fit for developers and testers who prefer integrating tests directly into development workflows.
Integration with CI/CD
REST-assured works seamlessly with CI/CD pipelines like Jenkins, GitLab CI, and GitHub Actions. Its compatibility with Java-based build tools such as Maven and Gradle means you can execute API tests alongside unit tests, ensuring smooth integration into the development cycle.
In June 2025, automation tester Nitika shared her experience of using REST-assured with GitHub Actions to detect issues early and scale testing effectively. Similarly, NashTech Global outlined a step-by-step process for setting up REST-assured tests in a GitLab CI pipeline.
"CI/CD integration automates your tests, running them every time code is committed, merged, or deployed. This gives you: Faster Feedback, Consistency, Scalability, Collaboration" – Nitika, Automation Tester
GitHub Actions, for instance, can automatically trigger REST-assured tests whenever changes are pushed to the main branch. This ensures continuous validation and catches API regressions before they reach production, creating a streamlined and reliable testing process.
Automation Features
REST-assured supports BDD syntax and integrates smoothly with testing frameworks like JUnit and TestNG. Using the Given-When-Then notation, it enables testers to create highly readable and structured tests. The library also offers features like:
- RequestSpecification: For reusable configurations.
- ResponseSpecification: For standardized response validations.
- Data-driven testing: Simplifies testing with multiple datasets.
- Parallel execution: Reduces execution time in CI/CD pipelines.
REST-assured supports multiple data formats, including JSON and XML, making it versatile for various API testing scenarios. For teams using Serenity BDD, REST-assured can organize tests into reusable "steps", allowing complex scenarios to be expressed in natural language while maintaining technical precision.
Cost and Scalability
One of the standout benefits of REST-assured is its cost-effectiveness. Being open-source, it eliminates licensing fees, making it an attractive option for organizations of any size. The primary costs involve Java expertise and infrastructure, which are typically offset by its seamless integration into existing environments.
"Rest Assured is a powerful and easy-to-use Java library that helps automate the testing of RESTful APIs. It lets you send requests, check responses, and validate results with minimal code." – Purushoth Kumar, Senior Automation Testing Engineer, Codoid
For larger projects, REST-assured scales efficiently with its data-driven testing and parallel execution capabilities. Its focus on code reusability allows teams to build comprehensive test suites without duplicating efforts, saving time and resources. Additionally, enterprise teams can enhance their testing workflows with custom reporting tools like Extent Report or Allure Report, providing detailed insights into API performance and ensuring compliance with documentation standards.
"Rest-Assured seamlessly integrates with CI/CD pipelines. Rest-Assured’s compatibility with popular CI/CD tools like Jenkins ensures that your API tests are automatically executed whenever there are code changes or deployments." – Oleksii Driuk, Author at ORIL
Tool Advantages and Disadvantages
API testing tools come with their own set of strengths and weaknesses, and understanding these trade-offs is key to improving CI/CD workflows. Your choice should depend on your team’s requirements, technical expertise, and budget.
Katalon Studio supports SOAP, REST, and GraphQL APIs with a low-code interface and AI-driven features that simplify the learning process. However, it can be memory-intensive during large-scale API load tests, and accessing advanced features requires upgrading to a paid plan starting at $183 per user per month.
Postman stands out for its intuitive interface and collaboration tools, particularly for REST API testing. It also offers robust workspace management. On the downside, it lacks advanced command-line interface (CLI) capabilities, and extended collaboration features come at an additional cost.
ReadyAPI provides a unified platform for functional and security testing of REST and SOAP APIs, along with native CI/CD integration via plugins. Despite these strengths, it struggles with seamless CI pipeline integration – especially with Bitbucket – and requires familiarity with Groovy for advanced tasks. Its pricing can also be a barrier for smaller teams [8, 57].
JMeter supports a wide range of protocols, including HTTP/HTTPS, FTP, SOAP, and REST, and excels in load testing. Being open-source, it eliminates licensing fees. However, it is resource-intensive for large-scale tests and relies on the Java Virtual Machine (JVM), which can be less effective in containerized environments.
REST-assured is an open-source library that integrates easily with Java testing frameworks and uses a Java-based Domain Specific Language (DSL) approach. While it is cost-efficient, it requires Java programming knowledge, offers limited support for SOAP APIs, and lacks a graphical user interface (GUI).
Here’s a quick comparison to help you decide:
| Tool | Supported Protocols | Key Strengths | Main Limitations | Cost Structure |
|---|---|---|---|---|
| Katalon Studio | SOAP, REST, GraphQL | Low-code, AI features, easy CI/CD setup | High memory usage, advanced features paid | From $183/user/month |
| Postman | REST | User-friendly, collaboration tools, mock servers | Limited CLI, extra costs for advanced features | Free to $49/user/month |
| ReadyAPI | REST, SOAP | Unified interface, native CI/CD plugins | CI pipeline issues, requires Groovy knowledge | Expensive for small teams |
| JMeter | HTTP/HTTPS, FTP, SOAP, REST | Powerful load testing, open-source | Resource-heavy, JVM dependency | Free |
| REST-assured | REST | Java integration, BDD syntax | Requires Java knowledge, no GUI, limited SOAP support | Free |
When choosing a tool, consider your technical requirements and budget. Open-source options like JMeter and REST-assured provide robust features without subscription fees but demand more technical expertise. On the other hand, commercial tools like Postman offer user-friendly interfaces and collaboration options, making them accessible to a broader audience. For teams heavily reliant on Java, REST-assured is often a natural fit, while organizations needing wide protocol support might lean toward Katalon Studio or ReadyAPI. Balancing these factors is crucial for optimizing API testing in your CI/CD pipeline.
Conclusion
Choosing the best API testing tool for your CI/CD pipeline hinges on factors like your team’s needs, technical skill set, and budget. Open-source options like JMeter and REST-assured are budget-friendly but may require more technical expertise. On the other hand, commercial tools such as Postman and Katalon Studio offer intuitive interfaces and collaboration features, often with paid plans. With this range of tools, teams can tailor their testing strategies to fit both their technical requirements and financial constraints.
Incorporating API testing tools into CI/CD workflows does more than ensure basic quality assurance – it elevates the entire development process. As Billy Shea puts it, "API testing is a critical safeguard that ensures your APIs’ functionality, security, and efficiency. Choosing the right API testing tool can maximize your product’s potential and create delightful user experiences". By automating validation for every code change before deployment, teams can catch issues early, iterate faster, and improve software quality.
For specific needs, REST-assured is ideal for Java-heavy environments, while JMeter shines in load testing scenarios.
Automating API testing within CI/CD pipelines not only accelerates release cycles but also reduces testing costs and bolsters deployment reliability. This approach aligns seamlessly with modern DevOps principles, emphasizing automation and efficiency. Organizations like TECHVZERO, known for their expertise in deployment automation and performance optimization, demonstrate how the right API testing tool can ensure scalable and dependable systems while minimizing downtime and speeding up time-to-market.
To make the most of API testing, start early in the development lifecycle, automate repetitive tasks, and cover functional, performance, and security aspects. With the proper tools and thoughtful implementation, API testing evolves from a potential hurdle into a strategic advantage, enhancing your software delivery process and driving success.
FAQs
What should I consider when selecting an API testing tool for my CI/CD pipeline?
When selecting an API testing tool for your CI/CD pipeline, it’s important to focus on a few critical aspects to ensure it aligns with your requirements:
- Integration and Compatibility: The tool should integrate effortlessly with your current CI/CD setup and support the specific protocols your APIs rely on. This ensures a smooth workflow without unnecessary adjustments.
- Features and Functionality: Opt for tools that offer a wide range of testing capabilities, including functional, performance, and security testing. The ability to simulate real-world user scenarios is also a valuable feature to look out for.
- Ease of Use: A straightforward interface paired with clear, well-organized documentation makes it easier for your team to get up and running without a steep learning curve.
Beyond these core factors, think about the tool’s ability to scale with your growing needs. Also, weigh the costs and licensing options carefully. While free tools may seem appealing, paid options often come with better customer support and advanced features that can save you time and effort in the long run. By keeping these considerations in mind, you can choose a tool that not only simplifies API testing but also enhances the efficiency of your CI/CD pipeline.
How do free tools like JMeter and REST-assured compare to paid options like Postman and Katalon Studio in terms of cost and usability?
Free tools like JMeter and REST-assured are excellent choices for budget-conscious teams. JMeter is completely free and comes with a graphical interface that supports multiple protocols. However, it does require a bit of technical know-how to set up and use effectively. On the other hand, REST-assured is a Java-based library, making it a great pick for those with programming skills, but it might not be as accessible for non-developers.
Paid tools, such as Postman and Katalon Studio, often offer free tiers but charge for advanced features and collaboration capabilities. Postman stands out for its intuitive design, making it accessible to both technical and non-technical users. Meanwhile, Katalon Studio offers a comprehensive testing platform for APIs, web, and mobile applications. However, its most powerful features are locked behind its paid plans.
While free tools are great for keeping costs low, paid options often provide a more polished experience, along with enhanced support and collaboration features – ideal for teams that value convenience and teamwork.
What are the benefits of integrating API testing into CI/CD pipelines, and how does it improve the development process?
Integrating API testing into CI/CD pipelines offers several advantages that make the software development process more efficient and reliable. One major benefit is catching defects early, which allows teams to address issues quickly. This not only cuts down on development costs but also helps avoid project delays. Automated API tests run consistently throughout the pipeline, maintaining code quality without slowing down the pace of deployments. The result? Faster and more dependable release cycles.
API testing also boosts test coverage and dependability by verifying functionality, performance, and security across different scenarios. This ensures that services work together seamlessly, creating a strong and scalable application ecosystem. By embedding API testing into CI/CD workflows, development teams can meet tight deadlines and deliver top-notch software that aligns with both customer needs and market demands.