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

Mockoon is the easiest and quickest way to design and run mock REST APIs.

Simulate APIs, integrations, and environments at enterprise scale.

Puppeteer is a Node.js library which provides a high-level API to control Chrome/Chromium over the DevTools Protocol.

The world’s first API testing platform that auto-generates unit test cases with dependency mocks from API calls. Using advanced AI, it simplifies test creation, debugging, and evolution, ensuring comprehensive coverage and boosting software quality.

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