Singapore is a Visa Waiver Program (VWP) country. Singaporean citizens do not need a visa for US tourism/business stays ≤90 days—including Alaska. They must obtain ESTA (Electronic System for Travel Authorization) online before travel (valid 2 years or until passport expiry). Apply at esta.cbp.dhs.gov ($21).
Requirements: machine-readable e-passport, return/onward ticket, no prior US visa denials/overstays. B1/B2 visa holders (issued before April 1, 2016) are ESTA-exempt. Alaska entry is identical to any US port—no separate Alaska visa exists. Always check current VWP/ESTA rules before booking.