The standard way, that works on most browsers, is to right click with the mouse and then select the “View source” option. It won’t work in all scenarios, though. For instance, when you’re using a mobile browser. There’s a trick you can use. It works on Chrome and Firefox, though it could work on other browsers too. You simply need to put “view-source:” on the URL before the domain name. Type that into your browser and it will display the source code directly.
Chrome && Firefox (Android)
You can also try apps available in Google play store or try http://viewsource.in. I hope this helped.