How to implement viewing doc xsl pdf files on the site?

Question

CodeIgniter

Good afternoon.
It is required to implement the ability to view files uploaded to the server in doc xsl docx pdf formats directly on the site without connecting online tools such as officeinline.
Because the site will spin in the local network without access to the Internet.
I searched on the Internet, suitable or something similar did not find. (or somehow I searched badly. I didn’t find it at all)

Answer 1

put the office (Libre, Open or forgot what it's called - domestic), something must be converted into a web format, this is just an office