How to Omit .html Extensions in Firebase Hosting URLs

Using cleanUrls

Configure hosting behavior | Firebase

This can be achieved by setting cleanUrls to true under hosting in firebase.json.

title=firebase.json

{
  "hosting": {
    "cleanUrls": true, //
    "trailingSlash": false // Whether to add a trailing slash
  }
}

You can access .html files using URLs without extensions.
/hoge → /hoge.html