auxlang 

Short for "International Auxiliary Language". a language created by a person or a group with the purpose of facilitating international communication. Typically, auxlangs are simple, regular and try to be culturally neutral. Well-known examples include Esperanto, Interlingua and Volapük.

People often measure the success of conlangs by their number of speakers, but that criterion works only for auxlangs, really.

auxlang by d'Acier September 7, 2011

auxlanger 

A person who has created one or more auxlangs (short for "International Auxiliary Languages", a.k.a. IALs). languages created in order to facilitate international communication.

Zamenhof is undoubtedly the most famous auxlanger of all times!

auxlanger by d'Acier September 7, 2011