If you're familiar with JavaScript you could use the mx.data.action() function to execute a microflow. Paste it in the console, using the developer console(F12), the next time you want to test it press on the up arrow and it will fetch the function from history. I use this for repetetive testing, because it saves me some seconds.
You could create a debug page where you can call your microflows directly. If you need parameters, create a non persistant helper that you can fill with data in a popup and then call your microflow with these attributes.
To know if the microflow is doing what it's supposed to do, is also a good case for unit testing. Although not suitable for once time testing/checking, in the long haul could save you time and automate your check time and time again.
You could create a rest service that calls the microflow within the application, so you can call it by browser or postman.