When creating a Contact through the Keap REST API you can supply a Timezone for the Contact, but it is limited to a non-comprehensive list of valid entries. You can find the list of acceptable values below.
Contact Timezones
Pacific/Pago_Pago
Pacific/Honolulu
America/Adak
Pacific/Marquesas
America/Anchorage
Pacific/Gambier
America/Los_Angeles
America/Santa_Isabel
Pacific/Pitcairn
America/Denver
America/Mazatlan
America/Phoenix
America/Mexico_City
America/Chicago
America/Guatemala
Pacific/Easter
America/Bogota
America/Havana
America/New_York
America/Caracas
America/Campo_Grande
America/Halifax
America/Goose_Bay
America/Santo_Domingo
America/Santiago
Atlantic/Stanley
America/Asuncion
America/St_Johns
America/Argentina/Buenos_Aires
America/Sao_Paulo
America/Miquelon
America/Montevideo
America/Godthab
America/Noronha
Atlantic/Azores
Atlantic/Cape_Verde
Europe/London
UTC
Europe/Berlin
Africa/Windhoek
Africa/Lagos
Asia/Damascus
Europe/Istanbul
Asia/Beirut
Asia/Gaza
Africa/Cairo
Asia/Jerusalem
Africa/Johannesburg
Asia/Baghdad
Europe/Minsk
Asia/Tehran
Asia/Yerevan
Asia/Baku
Asia/Dubai
Europe/Moscow
Asia/Kabul
Asia/Karachi
Asia/Kolkata
Asia/Kathmandu
Asia/Dhaka
Asia/Yekaterinburg
Asia/Rangoon
Asia/Omsk
Asia/Jakarta
Asia/Shanghai
Asia/Krasnoyarsk
Australia/Eucla
Asia/Irkutsk
Asia/Tokyo
Australia/Darwin
Australia/Adelaide
Australia/Brisbane
Australia/Sydney
Asia/Yakutsk
Australia/Lord_Howe
Pacific/Noumea
Asia/Vladivostok
Pacific/Norfolk
Pacific/Fiji
Pacific/Tarawa
Pacific/Majuro
Pacific/Auckland
Asia/Kamchatka
Pacific/Chatham
Pacific/Tongatapu
Pacific/Apia
Pacific/Kiritimati
Posted in: API