There's some frameworks that are available for old Windows desktop apps to run in the browser. It's main use is for old ERP systems that were originally written

There's some frameworks that are available for old Windows desktop apps to run in the browser. It's main use is for old ERP systems that were originally written for on-premise to be deployed in the cloud and browser based without needing to essentially rewrite everything. The one tech stack I know of that does this is IBM Websphere for Java apps (https://en.wikipedia.org/wiki/IBM_WebSphere https://en.wikipedia.org/wiki/IBM_WebSphere). One that isn't as smooth as the site in OP is Microsoft's Remote Desktop Service.