1. Postman
Postman is one of the most widely used API testing tools. It is known for its simple interface and powerful features. It helps developers design, test, and document APIs without writing excessive code. Whether you’re working with REST, SOAP, or GraphQL, Postman makes API testing straightforward. Using Postman, you can also collaborate remotely, so it is a go-to choice for startups and enterprises alike.
Top Features
- Automated testing with collections – You can create test scripts, organise requests, and run them in sequence. Perfect for regression testing.
- Mock servers for API responses – Postman offers a feature that simulates API behavior before development is complete. It reduces dependencies on backend teams.
- API documentation generation – It lets you generate and share API docs automatically, so you can stay aligned without extra effort.
- Collaboration tools – You can share API requests, test cases, and collections with team members. Crucial feature for seamless development.
- CI/CD integration – CI/CD integrations help run API tests in Jenkins, GitHub Actions, or other pipelines. Result: you identify issues much earlier.
Strengths
✔ Beginner-friendly UI – Even non-developers can test APIs easily.
✔ Massive community support – Tons of tutorials, forums, and plugins.
✔ Manual testing friendly – Lots of useful ways to set up environmental variables.
✔ Cross-platform – Works on Windows, macOS, and Linux.
✔ Team-friendly – Sharing test cases, mock servers, and reports is effortless.
”I personally enjoy using Postman cause you can have a test ready in minutes.”
Weaknesses
✖ Heavy on resources – Can lag with large collections or big datasets.
✖ Limited performance testing – Not ideal for load or stress testing.
✖ Advanced features require a subscription – Some collaboration tools are behind your reach if you are a small or mid-sized team.
“I use Postman a lot but very rarely for any sort of automated/serialised tests like you're describing. It's just not really able to do that well.”
“My recent foray into using Postman again resulted in frustration.”
User Ratings
⭐ Capterra: 4.7/5
⭐ G2: 4.6/5
2. SoapUI
SoapUI is the next tool on our list: a dedicated API testing tool designed for both REST and SOAP APIs. You can use it for functional, load, and security testing. SoapUI offers both open-source and pro versions. The latter provides advanced features like data-driven testing and API mocking. It’s a favorite among enterprises for its robustness and flexibility, especially for complex testing scenarios.
Top Features
- Comprehensive API support – Works with REST, SOAP, and GraphQL APIs.
- Data-driven testing – Integrates with Excel, databases, and other data sources for dynamic testing.
- Load testing – Simulates high traffic to test API performance under stress.
- Security testing – Scans APIs for vulnerabilities like SQL injection and XSS.
- API mocking – Simulates API behavior for early testing without backend dependencies.
Strengths
✔ Powerful for SOAP APIs – One of the best tools for SOAP-based services.
✔ Open-source version available – Free version is feature-rich for small teams.
✔ Advanced testing capabilities – Ideal for functional, load, and security testing.
✔ Strong community support – Plenty of tutorials, forums, and plugins available.
✔ CI/CD integration – Works seamlessly with Jenkins, Azure DevOps, and other pipelines.
"The tool is good and very helpful if you want to perform end to end API testing of your application. It supports both REST as well as SOAP protocol while creating a project which is under test."
Weaknesses
✖ Steep learning curve – Not as beginner-friendly as Postman.
✖ Outdated UI – The interface feels clunky and less modern compared to competitors.
✖ Pro version is expensive – Advanced features like data-driven testing require a paid subscription.
✖ Resource-heavy – Can slow down with large test suites or complex workflows.
"The file selection and management seems really dated and can be very annoying to navigate sometimes.”
User Ratings
⭐ Capterra: 4.5/5
⭐ G2: 4.4/5
SOAP UI and all the other tools we will analyse make API testing easier, but testing doesn’t stop there. Regression tests, UI tests, performance tests—keeping them all separate creates chaos. What you need is a Test Management System (TMS) to bring everything together. With a powerful TMS, you can track, execute, and analyse all test types in one place. Instead of losing your head between different tools and spreadsheets, you get a single source of truth for your entire QA process. Even using SOAP UI, you can still integrate it with aqua cloud and have your whole API testing streamlined.
This is where aqua cloud takes your test management to the next level. It brings API testing into your overall QA workflow. You can send API requests, capture results automatically, and track everything in one place. No more manual documentation—aqua logs test outcomes instantly for easy analysis. Plus, with aqua, you make your test management fully flexible, adaptable, and efficient by using powerful REST API, which lets you connect any tool. It integrates with your API tools, so you can run, track, and analyse API tests alongside manual and automated tests. Aqua goes beyond API testing; with AI-powered requirements, test case, and test data generation, you cut manual effort by 98% while keeping your testing fast, structured, and scalable.
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3. Swagger (Now SmartBear ReadyAPI)
Swagger, now part of SmartBear’s ReadyAPI suite, is another powerful tool for API design, testing, and documentation. It’s widely used for its ability to generate API documentation automatically from OpenAPI specifications. ReadyAPI extends Swagger’s capabilities with advanced testing features and makes it a top choice for enterprises.
Top Features
- API design and documentation – Automatically generates docs from OpenAPI specs.
- Automated testing – Supports functional, load, and security testing.
- Data-driven testing – Integrates with multiple data sources for dynamic testing.
- Mock servers – Simulates API behavior for early testing.
- CI/CD integration – Works with Jenkins, GitLab, and other pipelines.
Strengths
✔ Seamless design-to-testing workflow – Perfect for teams using OpenAPI standards.
✔ Excellent documentation capabilities – Automatically generates and updates API docs.
✔ Scalable for enterprises – Handles complex testing scenarios with ease.
✔ Strong OpenAPI support – Ideal for teams committed to API-first development.
"I’ve worked on projects with Swagger and projects without Swagger. I prefer the ones using Swagger."
Weaknesses
✖ High cost – ReadyAPI is expensive for small teams or individual developers.
✖ Steep learning curve – Requires familiarity with OpenAPI specifications.
✖ Overwhelming for beginners – Not as intuitive as tools like Postman.
"It's crazy to me that it's harder to write a Swagger file than it is to write the API itself. And there's a lot of tooling that benefits from Swagger, but... I've found they all work 80%."
User Ratings
⭐ Capterra: 4.6/5
⭐ G2: 4.5/5
4. JMeter
Apache JMeter is an open-source tool mainly used for performance and load testing. While it’s not specifically an API testing tool, it’s widely used for testing REST and SOAP APIs under heavy loads. JMeter is highly customisable and extensible, making it a favorite among developers and testers.
Top Features
- Load and performance testing – Simulates high traffic to test API performance.
- Extensible with plugins – Adds custom functionality through plugins.
- CI/CD integration – Works with Jenkins, GitLab, and other pipelines.
- Detailed reporting – Generates comprehensive test reports.
- Cross-platform support – Works on Windows, macOS, and Linux.
Strengths
✔ Free and open-source – No cost for small teams or individual developers.
✔ Highly customisable – Extensible with plugins and custom scripts.
✔ Excellent for performance testing – Handles high traffic with ease.
“JMeter is the best tool for performance testing. It’s free, powerful, and highly customisable.”
– u/PerfTestingGuru on Reddit
Weaknesses
✖ Steep learning curve – Not beginner-friendly.
✖ Outdated UI – The interface feels overwhelming and less intuitive.
✖ Limited functional testing capabilities – Not ideal for functional or security testing.
“JMeter is powerful, but the UI is a nightmare. It’s not the most user-friendly tool out there.”
– u/TestingNewbie on Reddit
User Ratings
⭐ Capterra: 4.4/5
⭐ G2: 4.3/5
5. Insomnia
Insomnia is a lightweight API testing tool popular for its simplicity and speed. It’s particularly popular among developers that need a quick and easy way to test REST and GraphQL APIs. It offers a clean, modern interface and supports collaboration features. We can say it is a great choice for small to mid-sized teams.
Top Features
- REST and GraphQL support – Works easily with both REST and GraphQL APIs.
- Environment variables – Allows dynamic testing with variables for different environments.
- Code snippet generation – Generates code snippets in multiple programming languages.
- Plugin system – Extends functionality with community-built plugins.
- Collaboration features – Enables team workflows with shared workspaces.
Strengths
✔ Lightweight and fast – Perfect for quick API testing.
✔ Intuitive interface – Easy to use, even for beginners.
✔ Strong GraphQL support – One of the best tools for GraphQL testing.
✔ Free version available – Offers essential features without cost.
"Insomnia all the way. Performance is quite good, I handle bulky JSONs in my daily work and Insomnia never breaks a sweat. UI/UX is decent too. Saved requests are managed nicely as well. Overall I've got no complaints with it and I see no reason to switch to another tool"
Weaknesses
✖ Limited advanced features – Lacks performance and security testing capabilities.
✖ Does not offer a web version – It is limited to an app.
✖ Collaboration features are paid – Team workflows require a subscription.
✖ No SOAP support – Only supports REST and GraphQL APIs.
✖ Forces users to have a cloud account – Local storage options are no longer available.
"Used Insomnia for a couple of years. We used it to test our APIs. Then they updated it and all my environments were messed up. Even when I tried to reload an old save."
User Ratings
⭐ Capterra: 4.6/5
⭐ G2: 4.5/5
6. Paw
Paw is a macOS-exclusive API testing tool known for its sleek design and powerful features. It’s ideal for developers who prefer a native macOS experience and need a tool for testing REST and GraphQL APIs. Paw offers dynamic values, code generation, and environment management. It is a favorite among macOS users.
Top Features
- REST & GraphQL support – Easily test and interact with both architectures.
- Dynamic values – Use variables and scripts for flexible testing.
- Code generation – Generate API call snippets in multiple languages.
- Environment management – Switch between dev, staging, and production.
- Extensions – Add custom functionality with plugins.
Strengths
✔ Deep macOS integration – Supports Touch Bar, shortcuts, and native UI.
✔ Advanced debugging tools – Detailed insights into requests and responses.
✔ Highly customisable – Dynamic values and code generation enhance flexibility.
"I just prefer Paw for being a native, high quality macOS app, instead e.g. Postman, Insomnia, etc."
Weaknesses
✖ macOS-only – Not available for Windows or Linux users.
✖ Limited collaboration features – Not ideal for team workflows.
✖ No performance or security testing – Focuses only on functional testing.
"Paw was pretty buggy for me. API-Collections are things I need to share with non-Mac people, I prefer a cross-platform tool for it. Paw‘s export extensions don’t work great."
User Ratings
⭐ Capterra: 4.7/5
⭐ G2: 4.6/5
7. Karatelabs
Karate DSL is an open-source API testing tool. It combines API testing, performance testing, and UI automation in a single framework. It’s built on top of Cucumber and allows testers to write tests in a simple, human-readable syntax. It is ideal for teams looking for a code-based testing solution.
Top Features
- API and performance testing – Combines functional and performance testing in one tool.
- Human-readable syntax – Easy to write and understand test cases.
- CI/CD integration – Works with Jenkins, GitLab, and other pipelines.
- Parallel execution – Runs tests in parallel for faster execution.
- Open-source – Free to use with no licensing costs.
Strengths
✔ Combines API and performance testing – Great for teams looking for a unified solution.
✔ Human-readable syntax – Easy for non-technical users to understand.
✔ Free and open-source – No cost for small teams or individual developers.
“Karate DSL is a hidden gem. It’s powerful, easy to use, and combines API and performance testing in one tool.”
– Review on G2
Weaknesses
✖ Requires coding knowledge – Not ideal for non-technical users.
✖ Limited UI – No graphical interface for test creation.
✖ Smaller community – Fewer resources compared to tools like Postman.
“Karate DSL is great for developers, but it’s not beginner-friendly. The lack of a UI makes it hard for non-technical users to adopt.”
– Review on Capterra
User Ratings
⭐ Capterra: 4.3/5
⭐ G2: 4.2/5
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Conclusion
So choosing the right API testing tool depends on several factors. You need to consider your team’s needs, technical expertise, and budget. Tools like Postman and Insomnia are great for beginners and small teams, while SoapUI and JMeter are gems for enterprise-level testing. To achieve 100% efficiency in your testing efforts, though, you need an all-around solution like aqua cloud.
