Postman - The Collaboration Platform for API Development
Runscope - Log, monitor and measure your API usage to solve API problems fast.
HTTPie for Terminal - Developers all around the world rely on HTTPie for API testing.
Thunder Client - Rest API client for VS Code, lightweight Postman alternative
API Tester - API Tester is the first mobile app to test any type of API on the go. Including REST, GraphQL, WebSocket, SOAP, JSON RPC, XML, HTTP, HTTPS.
Strapi - Manage any content. Anywhere. The leading open-source headless CMS. 100% JavaScript / TypeScript and fully customizable.