API testing tools are programs that help check if the parts of software applications (called APIs) work correctly. These tools make it easier for testers to see if APIs do what they’re supposed to do, like sending the right information or responding properly to requests. They help ensure that software systems communicate effectively with each other and perform as expected.
1. Bruno API Testing Tool
Bruno is a free and open source API testing client application for Linux, Windows, and MacOS. It prioritizes speed and seamless integration with Git. With Bruno, your collections are stored directly in a dedicated folder on your filesystem, and information about API requests is encoded using a straightforward plain text markup language called Bru.
2. Spectator API Tester Tool
Spectator is a free and open source API testing application for Linux. It is written in Vala and released under GNU General Public License v3.0.It comes with both composing requests and inspecting server responses, JavaScript Engine to execute user defined scripts at runtime and you can define variables in different environments. Using Spectator, you will get a smooth and efficient API testing experience.
3. Escambo API Testing Software
Escambo is a free and open source API testing software for Linux. It is written in Python and released under GNU General Public License v3.0.Using Escambo, you can create and test all HTTP-based APIs. It comes with Endpoint testing with GET, POST, PUT, DELETE, PATCH, query parameters and body. And also supports cookie, headers and authorization methods.
4. TestMace API Testing Application
TestMace is a free API Testing Development IDE for Windows, Linux and MacOS. It is also available in Paid versions. The basic version is completely free for commercial use also. Using this you can test your API, share your code and it comes with auto completion and syntax highlight. It comes with tests editor and scenarios, YAML format support, JS scripts and Embedded authentication methods. You can also import requests from cURL, Postman collections and importing API from Swagger and OpenAPI.
5. Insomnia API Testing REST Tool
Insomnia is a free and open source REST and GraphQL client for Windows, macOS and Linux. Using this you can create HTTP requests and get details about the response like status code, body, headers, cookies. It comes with workspaces and drag-and-drop requests support. Some of the important features are you can create reusable API keys or session IDs, global environment variables, code snippet generation, OAuth 1.0, 2.0 auth, NTLM and AWS authentication support, keyboard shortcuts, SSL client certificates, JSONPath and XPath, HTML preview and configurable proxy support.
6. Swell API Development Tool
Swell is a free and open source API testing and development software for Windows, macOS and Linux. It is released in MIT license. Using this you can test your API endpoints that served over streaming technologies. it supports Server-Sent Events (SSE), WebSockets, HTTP2, and GraphQL. Using this you can create GraphQL queries, mutations, and subscriptions. and View request timing and save it in collections.
7. Postman API Testing and Development tool
Postman is one of the best tool for API developers to test and develop APIs. The free version is best for individuals & small teams members. The pro version is for teams up to 50 users. It is available for Linux, Windows and MacOS. It provides API development tools to its users to design and mock, debug, test, document, monitor, and publish your APIs in a single software.
