Syng is an easy-to-use karaoke software. Just start the client and let your users connect via their web browser.
You can set up your own <em>Syng server</em> or simply use a publicly available one.

Songs can be searched and played from <em>YouTube</em>, an <em>S3</em> storage or <em>your local machine</em>.

You can play a variety of file formats, such as <code>mp3+cdg</code>, <code>webm</code>, <code>mp4</code>, ...