It's available as a Chrome (and maybe Firefox?) extension[0], then websites can use some JavaScript APIs to control it (with user permission of course)[1]. [0]

It's available as a Chrome (and maybe Firefox?) extension[0], then websites can use some JavaScript APIs to control it (with user permission of course)[1]. [0]: https://chrome.google.com/webstore/detail/google-cast/boadgeojelhgndaghljhdicfkmllpafd https://chrome.google.com/webstore/detail/google-cast/boadge... [1]: https://developers.google.com/cast/docs/chrome_sender https://developers.google.com/cast/docs/chrome_sender