Postman helps you be more efficient while working with APIs. Postman is a scratch-your-own-itch project. The need for it arose while one of the developers was creating an API for his project. After looking around for a number of tools, nothing felt just right. The primary features added were a history of sent requests and collections. A number of other features have been added since the initial release. Here is a small list.
Chrome has disabled externally hosted crx files so I can not give a link to the extension. To install Postman without the Chrome Web Store: