Top 8 REST API testing tools in 2026

Most of the web apps we use have a client-server architecture. The app itself is a client (frontend), and you need it to communicate with a server (backend) to transfer data. This communication is possible using HTTP requests since the client sends HTTP requests to the server.

Here is where REST APIs show up.

REST API: what is it?

In simple words, a REST API (REST stands for “representational state transfer”) is a set of regulations on how the communication between a client and a server must be realized. REST APIs contribute to the seamless communication between different services. 

Every server has endpoints that look outside. When a client communicates with a server, it happens via the endpoints. A REST API works like a CRUD when working with a database located on the server. Here are the steps: 

1. A client sends an HTTP GET, POST, PUT, or DELETE request to a server in an appropriate format.
2. The server receives the HTTP request and turns to the database.
3. The server forms a query to pull the needed data from the database.
4. The server sends the requested data to the client.

REST APIs represent a flexible and scalable way of integrating one web service with another one. Since REST APIs are standardized, you don’t have to format your data in any specific way. 

REST API advantages

The use of REST APIs has several essential advantages. Among them are:

• REST APIs are easy to understand. As said above, REST uses standard HTTP methods: GET, POST, PUT, and DELETE when communicating with a server. Thanks to a REST architecture, developers can simply display the needed data on the client-side, and manipulate it on the server-side.‍
• A client and a server are separated. The REST API architecture implies the separation of a UI from a client and a server. Due to this, a user interface can be easily moved to other platforms.‍
• REST APIs are scalable. Since a client and a server are isolated from one another, they can be scaled independently. Making changes to the database and tracking them doesn’t require too much effort.‍
• REST APIs ensure that the data is cacheable. To improve the overall performance, a REST API contributes to the cacheability of the stored data. The resources both on the client-side and the server-side are cacheable.

Top 8 API and REST API testing tools to try in 2022

Despite all the advantages RESTful web services have, it’s still important to make sure they are not vulnerable. Manual API testing is too complex and time-consuming. Below, we've compiled the list of the best and most commonly used API testing clients to look into to test your REST API in 2022.

#1. HTTPie

HTTPie is an API testing client in Python. It’s tailored for REST APIs testing and debugging. HTTPie makes the communication with HTTP servers, REST APIs, and web services seamless. You don’t need to have any specific skills to start using HTTPie.

Key features:

• User-friendly.
• Intuitive. 
• Web and desktop versions.
• Easy to learn.
• JSON support.

#2. Postman REST Client

Postman REST Client is an API testing platform for sending requests, viewing and inspecting responses, debugging REST APIs, etc. This API testing tool allows you to send HTTP requests to a development server. 

Key features:

• REST, SOAP, and GraphQL support.
• Data visualization.
• Built-in variables support.
• Multiple protocols support.

#3. curl

Curl remains one of the most essential developer tools in 2026 for testing APIs and transferring data directly from the command line. Even with the rise of AI API clients and GUI tools, curl is still the fastest way to debug requests, automate scripts, and validate endpoints in real environments.

Key features:

• Supports HTTP/HTTPS, WebSockets, FTP, LDAP, SMTP, IMAP, and many other protocols.
• Fully open-source with continuous updates from a large contributor community.
• Scriptable workflows for automated API testing, CI pipelines, and infrastructure tasks.
• Native support for modern authentication methods and secure connections.

#4. Swagger

Swagger, built around the OpenAPI Specification, continues to be a core standard for designing, documenting, and testing REST APIs in 2026. It has evolved from a simple documentation tool into a collaborative platform for API-first development, especially within distributed teams.

Key features:

• Full API lifecycle support: design, documentation, testing, and collaboration.
• OpenAPI Specification as the industry standard for REST API definitions.
• Interactive API documentation and automated mock servers.
• Role-based access control and versioning for enterprise teams.
• Integrations with modern CI/CD pipelines and cloud environments.

#5. Katalon Studio

Katalon Studio positions itself in 2026 as a unified automation platform for web, API, mobile, and desktop testing – combining low-code workflows with advanced scripting capabilities. It’s widely used by QA teams looking to automate testing without building complex frameworks from scratch.

Key features:

• Low-code test generation with reusable components and shared test assets.
• Built-in API testing with request creation and validation tools.
• AI-assisted test maintenance and failure analysis (newer releases).
• Seamless integration with CI/CD tools like Jenkins, Azure DevOps, and GitHub Actions.
• Cross-platform testing across multiple environments.

#6. SoapUI

SoapUI remains a well-established tool for functional API testing in 2026, especially for organizations working with both legacy SOAP services and modern REST or GraphQL APIs. It focuses heavily on reliability, automation, and integration with enterprise testing pipelines.

Key features:

• Open-source core with advanced Pro features for enterprise teams.
• REST, SOAP, GraphQL, JMS, and event-driven API testing support.
• Drag-and-drop interface combined with scripting for advanced scenarios.
• Integration with CI/CD workflows for automated regression testing.
• Extensive documentation and community resources.

#7. REST-assured

REST-assured continues to be a popular choice among Java developers for automated API testing, offering a clean DSL that simplifies writing readable test cases. In 2026, it’s commonly used alongside modern testing frameworks and AI-assisted QA workflows.

Key features:

• Fluent Java DSL for testing REST APIs.
• Support for JSON, XML, and schema validation.
• Integration with JUnit, TestNG, Serenity BDD, and modern testing stacks.
• Strong fit for automated testing within microservices architectures.

#8. Apigee

Apigee is an API testing tool used for designing, measuring performance, and scaling REST APIs. This testing platform offers can help you ensure seamless digital experiences for back-end services and serverless stacks.

Key features:

• End-to-end API lifecycle management: design, deployment, monitoring, and scaling.
• Advanced security policies, traffic management, and analytics dashboards.
• Developer portal for publishing and monetizing APIs.
• Integration with cloud-native stacks, microservices, and event-driven systems.
• AI-powered insights for performance monitoring and anomaly detection.

Instead of conclusion: A low-code approach to API testing

The quantity of APIs is rising together with the vulnerabilities that can damage cloud services. That’s why regular REST API testing is vital to ensure a proper security level. 

In addition to the traditional API testing tools, low-code platforms have already joined the game. They allow even non-tech people to create API tests visually to test the functionality you need. Adopting continuous API testing is a good practice to be able to detect API errors before someone else outside your team does it. 

Thanks to low-code, API testing is not something only developers and professional QAs can cope with. More people in your company can now take part in REST API testing process, thus relieving your development team from the need to distract from more critical tasks that add value to your business.