Mobile app

[lucaong]

You mean the home screen icon? If so, read this recent post here:

Favicon is not showing

Do you mean the home screen icon or the favicon (small icon shown in the browser tab)? Favicons are more or less a standard, while home screen icons are dependent on the specific OS: On modern Android phones, you should be able to use the App Manifest On Apple iOS you need to add <link rel="apple-touch-icon" sizes="..." href="..." >, and unfortunately you need one of this for each icon size In a progressive app I maintain, I had to produce iOS icons for all these sizes: 48x48, 72x72, 76x76, …