where can i find out where i bought a domain

i have a .es domain and i need to know where i got it from (i have completely forgotten the registrar).

EDIT: nevermind, i found a [.es] whois that actually worked. mods close. :)

For anyone still wondering, you can use a whois site

I usually use this site: http://www.whois.net/

yep, who is. I usually use who.is, or iwhois.com

Good luck :D