Timezone lookup: tzf-wasm 1.2.4 (MIT)
https://github.com/ringsaturn/tzf-wasm

Geographic timezone boundary data: OpenStreetMap contributors, via timezone-boundary-builder and tzf-rel. ODbL 1.0.
https://www.openstreetmap.org/copyright
https://opendatacommons.org/licenses/odbl/1-0/
https://github.com/evansiroky/timezone-boundary-builder
https://github.com/ringsaturn/tzf-rel

The simplified boundary data can differ from full boundaries by about 111 metres.