Most of the APIs require data to be gathered, analysed and updated on a daily or weekly basis (e.g. BIN lookup, IP Info, Geocode, IP blocklist, User-agent Info, Phone validate). Some need to connect directly to other networks (e.g. Phone verify, SMS verify, HLR lookup, Host Reputation, Currency Convert). These would be either impossible or quite difficult to implement in a library / local only environment. Others can just be a pain to implement (depending on your setup). Additionally, you gain the advantage of automatically inheriting updates to our algorithms and data sources.