Parsing on the backend, even when only considering United States addresses is incredibly difficult and error prone. There are apartment numbers, rural routes, PO boxes, circles, streets named after compass directions (i.e. North, South, East, West), streets whose direction names appear before or after the street itself (e.g. N. Main St. vs Main St. N.), military addresses, and the list goes on and on.

It's a terrible system really, and the only solution that I've been able to rely upon is having the user parse their own address and supply it to me. At least that way I don't have to spend hours looking through regex statements and edge case detection logic to figure out why a street address was parsed in a particular way.