Custom Web Interface

Is it possible to write my own custom Web front-end instead of the one written in Sencha EXT JS? If so what would be a good place to start learning how it currently works with Sencha. I've never worked with Sencha before but it looks like the UI is all output using JavaScript?

Thanks in advance.

Yes, all the UI is driven by JavaScript.

You can find documentation about ExtJS here: http://docs.sencha.com/extjs/6.0/

If you really want to completely re-write the web interface, you don't really need to know much about ExtJS. You can just implement interface in whatever way you want and call Traccar API directly from your code.

Great, is the Sencha UI using the API as well?

Yes, default web interface uses the API.