How to create a online service conversion of a file type to another type

Hello Everyone,

I want to create a website like or [URL=“”] PHP.

For this purpose, what should i do?

for ex:

1> Do i need to create a software and install that on server to convert a file? Then after uploading that file to server and then by using that software for conversion and giving it back to user using link?

I want to know the procedure for creating these kind of services.

Thank you

1> Correct.

Then i had to buy my own server for this purpose or hosting companies give this option to install software ?
If you can, Please give a useful link regarding this topic.