Top 10 API Testing Tools Every Developer Needs to Know in 2025

API testing is an essential aspect of modern software development. APIs (Application Programming Interfaces) enable different software systems to communicate with each other, making testing crucial to ensure seamless interaction, security, and performance. In 2025, developers have a wide array of powerful API testing tools to choose from. Here are the top 10 API testing tools every developer should know, with Apidog taking the lead as the most versatile option for API testing.

1. Apidog: The All-in-One API Development Platform

Apidog is an incredibly powerful API development and testing tool that stands out in 2025 for its all-in-one capabilities. It is perfect for developers who need to design, document, test, and mock APIs all within a single platform. What sets Apidog apart is its seamless integration of API design with testing and debugging tools, making it easy to write, test, and iterate APIs with minimal friction.

Key Features of Apidog:

• Unified Platform: Combine API design, testing, and documentation in one tool.
• Easy API Mocking: Simulate APIs before backend development.
• Automated Test Reports: Generate detailed reports for better test management.
• Collaborative: Share API documentation and testing environments with teams effortlessly.

Apidog’s testing capabilities allow developers to simulate API requests, validate responses, and automate testing processes, making it an indispensable tool for modern software development.

2. Postman

Postman has been a go-to tool for API testing for years, and it remains one of the most popular choices in 2025. It offers a range of features including automated testing, interactive API documentation, and a robust collection system to help organize and run API tests.

Key Features:

• Collection Runner: Automate multiple API tests with a single click.
• Environment Management: Test APIs in different environments with ease.
• Mock Servers: Simulate API responses to test various scenarios.

While Postman continues to be a strong contender, developers looking for a free and more integrated solution for API testing may want to explore other options, including Apidog.

3. SoapUI

For developers working with SOAP APIs, SoapUI is a must-have tool. SoapUI provides robust testing features for both REST and SOAP APIs, and its enterprise version adds security testing and API load testing capabilities.

Key Features:

• Comprehensive API Support: Test both SOAP and REST APIs.
• Security Testing: Built-in tools for testing API security vulnerabilities.
• Load Testing: Simulate heavy traffic to analyze API performance.

SoapUI is a powerful tool for comprehensive API testing, but its complexity might overwhelm beginners.

4. Swagger UI

Swagger UI is a tool designed primarily for testing and visualizing REST APIs. It’s widely used to create interactive API documentation. With Swagger, developers can generate API definitions using the OpenAPI specification, making it easy to automate tests and track API interactions.

Key Features:

• API Documentation: Generate interactive documentation with ease.
• Live Testing: Test API endpoints directly from the documentation interface.
• OpenAPI Specification Support: Simplifies API testing and integration.

Swagger UI is great for developers who need easy-to-read documentation and live testing within a simple UI.

5. Katalon Studio

Katalon Studio is a powerful, easy-to-use API testing tool that supports not just API but also mobile, web, and desktop application testing. It’s a popular choice for automated API testing due to its feature-rich environment and simplicity.

Key Features:

• Cross-Platform Support: Test APIs along with web and mobile apps in one tool.
• Data-Driven Testing: Automate tests with data-driven functionality.
• Built-In Reporting: Provides detailed test reports to help developers monitor API health.

For teams working across multiple platforms, Katalon Studio is a solid choice.

6. Apigee

Apigee by Google Cloud is a comprehensive API management tool that includes API testing as part of its suite. It’s an excellent choice for developers working on large-scale projects and API ecosystems, providing both testing and advanced analytics.

Key Features:

• API Analytics: Monitor and analyze API usage and performance.
• Security Testing: Ensure your APIs are secure with integrated security testing tools.
• Scalable: Supports testing for APIs in large systems.

Apigee is well-suited for enterprise-level applications where monitoring and analytics are just as crucial as testing.

7. Paw

Paw is an intuitive API testing tool for macOS users, known for its sleek user interface and powerful features. It’s great for developers who prefer a more visual approach to API testing and documentation.

Key Features:

• Rich User Interface: Easy-to-use interface for testing APIs with detailed visualization.
• API Code Generation: Generate client code for APIs in multiple languages.
• Native macOS Application: Seamlessly integrates with macOS ecosystem.

Paw’s native macOS support makes it a great option for developers who want a polished API testing experience.

8. JUnit + RestAssured

For developers who prefer writing unit tests, JUnit combined with RestAssured is a popular option. RestAssured is a Java library for testing REST APIs, and when paired with JUnit, it allows for powerful and flexible API testing.

Key Features:

• Code-Based Testing: Write API tests directly in your Java code.
• Rich Assertions: Supports extensive assertions to validate API responses.
• Customizable: Highly flexible for advanced testing scenarios.

RestAssured is ideal for developers familiar with Java who want to integrate API tests directly into their test suite.

9. RedwoodHQ

RedwoodHQ is a testing framework that supports both manual and automated API testing. It’s a great choice for developers who prefer an open-source, customizable solution.

Key Features:

• Hybrid Testing: Supports both manual and automated testing workflows.
• Customizable: Highly configurable to suit different development needs.
• Open-Source: Free to use and modify according to your requirements.

RedwoodHQ is a great option for developers looking for a low-cost, flexible API testing solution.

10. JMeter

Apache JMeter is a well-known open-source tool designed for performance testing and API load testing. While it is primarily used for performance testing, it’s a valuable tool for API testing when performance and scalability are the primary focus.

Key Features:

• Load Testing: Simulate large numbers of API requests to measure performance.
• Distributed Testing: Run tests on multiple machines to simulate real-world traffic.
• Extensible: Support for numerous plugins and integrations.

JMeter is the go-to tool when API performance and load testing are at the forefront of your testing strategy.

Conclusion

As APIs continue to evolve in 2025, having the right tools to test and manage them is essential for every developer. Apidog leads the charge with its all-in-one platform for API development, testing, and documentation, making it the top choice for developers in the field. Other tools like Postman, SoapUI, and Katalon Studio provide strong support for specific use cases, whether it’s automated testing, performance testing, or SOAP support. Choose the right API testing tool based on your needs, and ensure that your APIs are robust, secure, and high-performing.

Ready to enhance your API testing process? Start using Apidog today to streamline your API workflow and improve collaboration within your team!