<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title> Welcome </title> </head> <body> <h1> Welcome </h1> <p> Loading... </p> </body> </html>
You can type viewhtmlonline.com in front of any url you're browsing and it will show you the source.
viewhtmlonline.com
For example: viewhtmlonline.com/https://temp.cool
viewhtmlonline.com/https://temp.cool