Developers of skills for the Alexa platform no longer need an Echo, Tap, or Dot to test their code. Amazon has launched the Echosim.io site that uses a virtual Echo to test code. It runs just like an Alexa device, but totally in the browser.
Users open the website and log into an Amazon account. This requires allowing the site to have access to the user's laptop microphone. Commands are issued to the virtual Echo by voice, clicking and holding the microphone button on the screen while speaking.
Amazon has a complete guide for developing skills for Alexa. Skills are extensions to the Alexa platform as installed on enabled devices. It's now possible to develop skills completely without an Amazon device.
While intended to be used by developers for testing code, it is functional for anyone wishing to test the Echo. In our testing it works in Chrome and Safari on the Mac.