TZ / World clock

Typeface: DM Sans, distributed by Google Fonts under the SIL Open Font
License 1.1. Self-hosted through Fontsource. The license is included at
/fonts/DM-Sans-LICENSE.txt.
https://fonts.google.com/specimen/DM+Sans

Map geometry: Natural Earth 5.1.2, public domain.
https://www.naturalearthdata.com/
Distributed as @cublya/world-atlas 3.0.0-beta.2 (ISC).
https://github.com/cublya/world-atlas

Time-zone boundaries: timezone-boundary-builder, distributed through
geo-tz 8.1.9. Derived from OpenStreetMap contributors, under the Open
Database License (ODbL) 1.0. The unmodified current/future boundary database
and its index are available in /tz-data/ on this site.
https://github.com/evansiroky/timezone-boundary-builder
https://www.openstreetmap.org/copyright
https://opendatacommons.org/licenses/odbl/1-0/
https://github.com/evansiroky/node-geo-tz

Browser lookup: browser-geo-tz 0.2.3, MIT.
https://github.com/kevmo314/browser-geo-tz

Clocks use the IANA time-zone rules included in your browser. Time is
checked against this site's server on load and every five minutes;
when offline, clocks continue using the last synchronized time or your
device's clock. Clock synchronization is approximate to network latency.

The current/future database groups zones with equivalent current and
future clock rules. Thus the identifier returned for a selected area can
name a different representative city, while its current time is the same.
City pins use their own named IANA zones. Map boundaries are generalized
for display. Detailed click lookups use the separate boundary database.
Open-ocean readings use nautical offsets; they are not shipboard time.
This app displays current time, not historical local-time calculations.