Uptime Kuma is an easy-to-use self-hosted monitoring tool.

Requestly is an open-source tool that simplifies API development, testing, mocking, and integration for developers and QAs.

Code, test, and deploy synthetic monitoring at scale.

Built for developers and testers alike, SoapUI is the only open source tool that covers the entire testing spectrum (functional, security, load, mocking).

Voiden is a developer-first API client with local storage, Git-integrated, all based on markdown + offline support.

Testing and validating REST services in Java is harder than in dynamic languages such as Ruby and Groovy. REST Assured brings the simplicity of using these languages into the Java domain.