JSViz is audio visualizer in Javascript and HTML. It should be compatible with majority of web browsers, and is very small and simple.
While this does support almost every device with a web browser, it may not run correctly on certain devices. This has only been tested on chrome, and on chromes lighthouse thingy. Thats it. So if you are going to use this for something like that, please test it first.
There is also no queueing system, so you cannot add multiple audio tracks and play it one after the other automatically.