Milkman

Heavily inspired by Postman, Milkman is a lightweight and quite practical JavaFX-based application designed to offer web developers a faster way to create API test cases.
Since it’s inspired by Postman, it’s no surprise that the tool offers a similar set of functionalities, even though it’s definitely not as feature-packed as Postman. For example, Milkman allows you to send requests to the webserver and get back responses.
Developers can create any number of test cases that can be effortlessly managed. What’s more, users can also create and manage collections (workspaces) of integration test cases. Just like Postman, Milkman is basically a plugin that comes wrapped in a more extensible and a faster app.
In its current form, the app does not require installation and can be run directly after unzipping its archived package. Right off the bat, it’s quite clear that this app is simpler than Postman. Once launched, developers are greeted by a compact main window with a modern GUI. In the upper part of the main window, users can create new or toggle between already existing workspaces, import projects (from Postman), and select or switch between environments.
The app also boasts an Options menu that provides users with the possibility of choosing between two GUI themes, and of switching the Code Editor/Viewer on or off. Developers can also use proxies, and even add IP on a simple ignore list.
All in all, Milkman doesn’t impress in terms of features. However, it should be taken into account that the app was purposefully designed to be as simple and fast as possible. The developer behind the project itself describes it to be a “jump-in and do something, then leave” type of application.