How to add apps without jailbreaking?

I believe there's an application you can download on PC without having to jailbreak your apple device? Does anyone have a link to it or something or any other way to add apps without jailbreak?

the only way that i know of is to use itunes to download apps to your computer and then install them onto your idevice

You can use iFunBox to add apps without using iTunes (so official ones, registered to your account).
However, to install pirated/cracked apps, you need to jailbreak. There is no alternative.