'''Jan Koum''' ({{lang-ruuk|link=no|Ян Кум}}; lahir 24 Februari 1976) adalah [[CEO]] dan pendiri [[WhatsApp]] bersama [[Brian Acton]]. WhatsApp merupakan aplikasi pesan bergerak yang diakuisisi oleh [[Facebook Inc.]] pada Februari 2014 dengan nilai $19 miliar.<ref name="forbes.com">{{cite web|url=http://www.forbes.com/sites/parmyolson/2014/02/19/exclusive-inside-story-how-jan-koum-built-whatsapp-into-facebooks-new-19-billion-baby/ |title=Exclusive: The Rags-To-Riches Tale Of How Jan Koum Built WhatsApp Into Facebook's New $19 Billion Baby |publisher=Forbes |date=2009-02-24 |accessdate=2014-02-20}}</ref><ref>{{cite web|url=http://www.abc.net.au/news/2014-02-20/facebook-acquires-whatsapp-in-19-billion-deal/5272010 |title=Facebook acquires WhatsApp in massive deal worth $19 billion - ABC News (Australian Broadcasting Corporation) |language={{it icon}} |publisher=Abc.net.au |date= |accessdate=2014-02-20}}</ref><ref>{{cite web|author= |url=http://mashable.com/2014/02/19/whatsapp-founders-jan-koum-brian-acton/ |title=WhatsApp Founders Are Low Key — And Now Very Rich |publisher=Mashable.com |date=2013-10-26 |accessdate=2014-02-20}}</ref> Koum dibesarkan di sebuah desa di luar [[Kiev]], [[Ukraina]]. Ia pindah ke [[California]] bersama ibu dan neneknya tahun 1992.<ref>{{cite web|last=Rowan |first=David |url=http://www.wired.co.uk/news/archive/2014-02/19/whatsapp-exclusive |title=WhatsApp: The inside story (Wired UK) |publisher=Wired.co.uk |date= |accessdate=2014-02-20}}</ref> Saat ini Koum memegang 45% saham WhatsApp dengan nilai mendekati US$7 miliar.<ref name="CNN"/>
