Most foreign states have an embassy or a consulate in Budapest, Hungary. Those countries that don't, mostly maintain representations in nearby Vienna. There is an „embassy district" in Budapest, near Heroes' Square, where there are 15+ embassies. Some embassies have a fortified security zone built around them, such as the American Embassy on Szabadság tér, and the British embassy in Harmincad utca.
The embassies in Budapest listed below are broken down by continent: you can find here all embassies of European, American, Australian, Asian an African countries.