Top 10 API Testing Tools in 2025: A Complete Guide

As software applications become more complex and interconnected, a new behind-the-scenes player has emerged as essential: the API.

At HyperTest, we were curious about the variety of API testing tools available today. To satisfy our curiosity, we decided to compare the top 10 performers. This blog post focuses entirely on our comparison criteria and the discoveries we made. But before we get into the details, let's set the stage.

What is an API?

The term 'Application' refers to any software with a specific function, while 'Interface' can be conceptualized as a service agreement between two applications.

Example of APIs

Let’s understand APIs with the help of some examples. There are abundant of APIs in various domains. Here are a few:

• Web APIs: These are used to enable communication between web servers and clients. For instance, the Twitter API allows developers to access and interact with Twitter's features, such as retrieving tweets or posting new ones.

• Database APIs: These allow applications to communicate with databases. The Java Database Connectivity (JDBC) API enables Java applications to interact with various databases using a standardized interface.

  
  

• Third-Party APIs: Many companies offer APIs to allow developers to integrate their services into other applications. The Google Maps API lets developers embed interactive maps into their websites or apps.

  
  

In essence, APIs are the bridges that enable software components to collaborate and work together seamlessly, enhancing the capabilities and functionalities of applications across different domains.

What is API testing?

API testing, an integral part of software quality assurance, involves testing APIs to verify their functionality, reliability, performance, and security. Unlike traditional GUI testing, API testing focuses on the business logic layer of the software architecture. This type of testing is crucial as it helps detect issues early in the development cycle, leading to more stable and reliable software applications.

Benefits of API testing

➡️Finding bugs at an early stage of software development: Having access to the application without a user interface or users to engage with the system is a significant advantage of API testing. It provides teams with early visibility into flaws and faults, enabling developers to address them before any impact on the interface occurs.

➡️Saving time and Reducing testing time: API testing stands out for its rapid result delivery, leading to early detection of flaws and ultimately lowering overall testing costs.

➡️Language Independence: Utilizing XML or JSON for data communication in API tests ensures language independence. This flexibility allows automation of API testing in the application using any core programming language.

➡️ Better Application Coverage: Testing APIs with all possible schema and data is the quickest way to test every scenario and cover application code quickly like functions, branches and statements. API tests written right can truly test the intersection between different components of an application quickly, reliably and consistently. 

Challenges in API Testing

API testing, while essential, presents unique challenges that can impact the efficiency and effectiveness of your software testing process. Understanding these challenges is key to selecting the right tools and strategies.

• Understanding API Specifications: 

  APIs can be complex, with intricate specifications and rules. Testers must thoroughly understand these specifications to ensure comprehensive testing. This includes grasping various request and response formats, HTTP methods, and error codes.

  
  

• Handling Diverse API Standards: 

  With the existence of multiple API architectures like REST, SOAP, GraphQL, and others, a testing tool must be versatile enough to handle these varied formats.

  Each type of API has its own set of protocols and data formats (like JSON, XML), adding to the testing complexity.

  
  

• Data Validation:

  Ensuring the correctness of data returned by APIs is another challenge. This includes validating response data against expected data formats, schema, and values. Incorrect data can lead to application failures.

• Environment and Configuration Management: 

  Setting up different testing environments for various stages of development (like staging, production) and managing configurations for each can be complex and time-consuming.

• Test case maintenance:

  APIs are frequently updated. Keeping tests up to date with these changes, especially in a fast-paced agile environment, is challenging and requires tests to be easily modifiable and extensible.

Now that we have covered all the foundational knowledge to understand the tools better, let's have a quick overview on some of the most widely accepted tools:

1. HyperTest - API Testing Tool:

HyperTest is the preferred integration testing platform for modern agile teams. It regresses all your APIs by auto-generating integration tests using your network traffic without investing time in generating the test cases.

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Backed up by dev teams from Nykaa, Porter, Yellow.ai, Urban Company, Zoop.one, Skaud etc, HyperTest makes it impossible for devs to introduce a breaking change that is not reported back to QA teams.

It tests a user-flow, across the sequence of steps an actual user will take in using the application via its API calls. It detects every issue during testing in less than 10 mins, that other written tests would definitely miss.

1.1 Key Features:

• Test GraphQL, gRPC & REST APIs

• Test Queues or Async flows like Kafka, RabbitMQ, SQS and others

• Run end to end API tests locally pre-commit. No need to create or manage test environments

• Cover every functional scenario and edge cases with code coverage reports

• Integration with any CI/CD tool like Jenkins, Circle CI, GitLab etc

  
  

Pricing: Free for one service; Followed by flexible paid plans

2. Postman - API Testing Tool:

Postman is an API development environment which is divided into three parts – Collections, Workspaces, and Built-in Tools. Postman collections enable you to execute requests, conduct testing and debugging, automate tests, create mocks, document, and monitor APIs.

It will also allow you to share the collections, set permissions, and manage participation in multiple workspaces.

2.1. Key Features:

• Although it requires some coding effort, it anyways helps in automated testing

• Assists in exploratory testing

• It is compatible with Swagger and RAML (RESTful API Modeling Language) formats.

• It supports knowledge sharing within the team

• Run, test, document, and monitoring features

2.2. Limitations:

• Limited to basic API testing purposes.

• Suitable for tasks like validating API responses, status codes, and contracts.

• Not equipped for performance testing.

• Lacks necessary insights and metrics for performance analysis.

• Postman test scripts are challenging to repurpose.

Website: https://www.postman.com/

3. Katalon - API Testing Tool:

Katalon Studio is an automation tool for API, Web, Desktop testing and Mobile testing. It offers straightforward deployment by consolidating all frameworks, ALM integrations, and plugins into a single package.

The capability of combining UI and API/Web services for multiple environments (Windows, Mac OS, and Linux) is also a unique advantage of Katalon Studio among the top API tools.

3.1. Key Features:

• Endorses REST, SOAP requests, and SSL client certificates

• Incorporates AssertJ support for crafting fluent assertions in BDD style

• Facilitates test import from Swagger (2.0 & 3.0), Postman, WSDL, and WADL

• Enables API test data setup through UI testing

• Applicable for both automated and exploratory testing.

3.2. Limitations:

• Katalon operates as a proprietary tool with restricted features in its free version.

• Due to a smaller user base, community support for Katalon is relatively limited.

• Finding solutions for intricate scenarios can be challenging.

  
  

• Katalon lacks support for various scripting languages.

Website: https://katalon.com/

Pricing: Free and Flexible paid plans available

4. Apigee - API Testing Tool:

Apigee stands out as a versatile cross-cloud API testing solution, driven by JavaScript. Developers and testers can seamlessly access its functionalities through various editors. Tailored for the needs of robust and intricate digital businesses, Apigee excels in handling APIs with substantial data.

Its capability to analyze API traffic, response times, and potential error rates makes it adept at swiftly identifying and addressing performance-compromising issues.

4.1. Key Features:

• Facilitates monitoring, implementation, and extension of API designs

• Utilizes a multi-step process driven by JavaScript

• Identifies performance issues through the tracking of API traffic, error rates, and response times

• Streamlines the creation of an API proxy based on open API specifications, deployable in the cloud

4.2. Limitations:

• Apigee requires a significant number of resources, leading to a high initial expense for deploying it on-premises.

• Employing a container-based approach could streamline the installation and deployment process.

Website:https://cloud.google.com/apigee

Pricing: Free and paid plans available

5. JMeter - API Testing Tool:

JMeter is a freely available software designed for load and performance testing of applications. Operating on a cross-platform basis and functioning at the protocol layer, it serves as a versatile tool for developers.

Notably, JMeter can be employed as a unit-test tool for JDBC database connection testing. With a plugin-based architecture, it facilitates the generation of test data and supports a Command-line mode, particularly beneficial for Java-compatible operating systems.

5.1. Key Features:

• Enable caching and offline playback of test results

• Seamless integration with CSV files, allowing the team to swiftly generate unique parameter values for API tests

• Integration of API tests into the CI pipeline facilitated through JMeter and Jenkins

• Applicable for performance testing of both static and dynamic resources

5.2. Limitations:

• JMeter's user interface is often reported as not being user-friendly, causing challenges during test script execution.

• JMeter tends to use a significant amount of memory, leading to frequent performance issues when compared to alternative API automation tools.

• JMeter's scripting process for API testing is more intricate in comparison to other available API testing tools.

Website: https://jmeter.apache.org/

Pricing: Free

6. Rest Assured - API Testing Tool:

REST Assured is a freely available, open-source Java library utilized for the testing and validation of RESTful APIs. It stands out for its user-friendly approach in Java settings, making it a popular option among developers and testers dealing with REST services.

6.1. Key Features:

• Accommodates all the main HTTP methods like GET, POST, PUT, DELETE, facilitating interactions with a variety of API endpoints.

• REST Assured enables predefined configurations for requests, including base URI, headers, query parameters, and authentication, which can be reused in various tests.

• It offers the capability to examine various elements of API responses, such as status codes, headers, the body of the response, and timing.

  
  

• Comes with inbuilt capabilities for managing JSON and XML responses, which are prevalent in today’s APIs.

6.2. Limitations:

• Does not specifically cater to the testing of SOAP (Simple Object Access Protocol) APIs.

  
  

• To use REST Assured effectively, a solid understanding of Java programming is necessary.

Website: https://rest-assured.io/

Pricing: Free

7. Karate DSL - API Testing Tool:

Karate DSL, an open-source API testing framework, utilizes Behavior Driven Development (BDD) and Gherkin syntax for API test automation.

This approach, distinct from other BDD tools like JBehave or Cucumber, provides pre-defined step definitions, enabling easy test creation, even for those with minimal coding experience.

7.1. Key Features:

• Supports BDD Syntax

• It is beginner friendly as it requires minimal coding experience.

• Integrates with the Gatling framework for performance checks.

• Features multi-thread parallel execution.

7.2. Limitations:

• May require learning new scripting syntax.

• Absence of IntelliSense support in integrated development environments.

• Identifying code errors can be complex

Website: https://www.karatelabs.io/

Pricing: Starts at $64/month

8. SoapUI - API Testing Tool:

SoapUI, a prominent API testing solution, is favored by many businesses for its ability to adhere to specific protocols and functionality needs. It supports a wide range of features and is compatible with REST and SOAP APIs.

SoapUI specializes in API performance, security testing, and mocking, ensuring efficient and secure API operations.

8.1. Key Features:

• Evaluates API stability under high user loads.

• It provides insightful metrics analysis for easy decision-making.

• Generates test simulations and analyzes performance data.

• Includes checks for SQL injection and cross-site scripting.

• Mimics API service behaviors for thorough testing

8.2. Limitations:

• Some users report stability concerns, leading to crashes or erratic behavior during tests.

  
  

• The interface and features can be challenging for beginners in API testing.

  
  

• SoapUI depends on Web Services Description Language (WSDL) for web service testing, which can be a limitation if WSDL files are not well-defined or available

Website: https://www.soapui.org/

Pricing: Available for free trial and then a yearly license purchase of $659

9. Blazemeter - API Testing Tool:

BlazeMeter is an advanced API testing tool that offers a range of features to streamline and optimize the testing process. It's designed to cater to various testing needs, from performance testing to API monitoring and functional testing.

9.1. Key Features:

• Comprehensive testing tools on a single platform.

• AI-driven test data generation for improved accuracy.

• Easy integration with IDEs.

• World-class device lab for extensive functional testing.

• Robust API testing and monitoring features.

9.2. Limitations:

• Pricing may be higher for smaller teams or startups.

  
  

• Steep learning curve: To effectively analyze BlazeMeter reports, users need to have a good understanding of the tool and its data.

Website: https://www.blazemeter.com/

Pricing: Free plan, followed by Pro and Contract-based plan.

10. Rest Console - API Testing Tool:

This Chrome-based REST/HTTP Client tool is designed for users to easily design and test custom HTTP requests with any RESTful API service.

10.1. Key Features:

• Users can easily craft POST or PUT bodies with raw input.

• It features a user-friendly interface for modifying custom headers.

• The tool simplifies the process of creating query parameters.

• It's versatile for various authentication methods including Plain, Basic, and OAuth.

  
  

10.2. Limitations:

• User interface is somewhat outdated and has limited accessibility.

• Still in the early stages of development.

  
  
  
  

Website: https://github.com/ahmadnassri/restconsole

Pricing: Free

The Only Tool You Need to Test Your APIs

Don't have much time? Get a snapshot of the best API testing tools with our quick comparison chart.

While these are some really great tools, HyperTest is the only API testing platform that lets you pinpoint to the exact cause of failure even in a complex set of services. Moreover, it doesn't require your whole system to be up and running while it catches all the regressions between your stable version and your newly updated one. Its unique approach to API regression discovers every API error for developers before release.

Learn about how HyperTest helped a FinTech App serving over half a million users to catch every critical bug before production.