Swagger-UI v2 provides a convenient way to work with object-typed requests in a form:

To activate this option, go to the Settings icon located in the top-right corner of the page, expand it and enable the "Use forms for request input" checkbox:


The "What if I want to use the previous version?" section of "Working with Swagger UI v2 and v3" explains how to open the old Swagger-UI v2 in a live view.