Counting down to midnight, January 1 — in your own time zone.
Yours — the clock counts to January 1, 00:00 in your device’s time zone. The planet takes 26 hours to finish the job: Kiritimati (UTC+14) celebrates first, the uninhabited Baker Island (UTC−12) last. Party accordingly with the world clock.
On January 2 it starts the 364-day march to the next one. The tool never needs a year typed into it.
Entirely in your browser. Dates you type are never sent anywhere — there is no server doing the math, no analytics watching you do it.