Can anyone tell me how to compile HTML, CSS, JS, PHP and SQL, USING ONLINE COMPILER FOR FREE, IF AVAILABLE?

Answer 1

For all the above web development languages, the w3schools.com platform is right for you. It is very convenient for writing code and in teaching programming languages.

Answer 2

Try phcode.dev - it's lightweight and straightforward. You can use it online for free and/or download it on PC for free. No need to signup whatsoever.