WebAssembly is a bytecode format intended to be executed in a web browser. This allows an application to be deployed to a device with a compliant web browser without going through any explicit installation steps. The application will be running inside a secure sandbox in the web browser, making it appropriate for applications that do not need full access to the device capabilities, but benefits from a swift and uncomplicated installation process.
When Qt 5.11.0 is released, we also plan to release a technology preview of our Qt for WebAssembly port, allowing you to try out running Qt applications directly inside the browser window.
Today we published the beta release of this port, and it is available as a source bundle in your Qt account download area. Feedback on this beta release would be greatly appreciated.
There is additional info in in the official wiki page, including information on how to set up an environment and build the package.