vSphere UI (HTML5)
6.5 - please refer to section below - vSphere Web Client (Flash)
6.7 - To launch vSphere UI (HTML5) and force it to use a localized language or to switch to English:
ESXi Host Client
To launch the Host Client and force it to use a localized language or to switch to English:
vSphere Web Client (Flash)
https://client_hostname/vsphere-client
/?locale=en_US
/?locale=de_DE
/?locale=fr_FR
/?locale=ja_JP
/?locale=ko_KR
/?locale=zh_CN
https://client-hostname/vsphere-client/?locale=fr_FR
vSphere 6.5
Flash - https://client-hostname/vsphere-client/?locale=fr_FR
HTML5 - https://client-hostname/ui/?locale=fr_FR