Likely to be a dump of whatever functional testing tools I experiment with... time will tell.
Karate is the only open-source tool to combine API test-automation, mocks and performance-testing into a single, unified framework. The BDD syntax popularized by Cucumber is language-neutral, and easy for even non-programmers. Besides powerful JSON & XML assertions, you can run tests in parallel for speed - which is critical for HTTP API testing.
Go here for more details.
Postman is the collaboration platform for API development. Postman simplifies each step of building an API and streamlines collaboration so you can create better APIs—faster.
Go here for more details.
Bruno is a Fast and Git-Friendly Opensource API client. Bruno stores your collections directly in a folder on your filesystem. We use a plain text markup language, Bru, to save information about API requests.
Go here for more details.
Robot Framework is a generic test automation framework for acceptance testing and acceptance test-driven development. It is a keyword-driven testing framework that uses tabular test data syntax.
My initial exploration with Robot Framework came to an abrupt end... and now the scripts I created no longer work. sigh I'll focuse on this one more in the future.
Go here for more details.