X Steps Recorder - A clone of Microsoft's Problem Steps Recorder, but for linux.
Postman - The Collaboration Platform for API Development
Folge - The fastest tool for creating step-by-step guides.
Insomnia REST - The most intuitive cross-platform REST API Client ð´
Snagit - Screen Capture Software for Windows and Mac
RESTer - A REST client for almost any web service (Firefox and Chrome extension).