English has so much slang for friend, haha. This is a mix of American and British. Most of these are used as jokes, though I've bolded well-used ones. Some are for specific types of relationships as well, so look into them before you use them!

Dude, bro, broski, man, bud, buddy, pal, bub, bubba, homie, brother, homeslice, brobama, fam, lad, mate, bloke, chap, fella, guy, bruv 

Ok you have the English so I will add some of the Afrikaans ones.

Maat, Pel, Vriend, Choma.

Hola Alberto! 

Here in Serbia, friends call each other "Brate!" which literally translates as brother in English, but it is a colloquial term for friend, mate, buddy.