timezonefinder-data

The timezone boundary data used by timezonefinder, compiled from timezone-boundary-builder releases into the binary format described in the data format reference.

pip install timezonefinder installs this package automatically - there is nothing extra to do. It is a separate distribution so that a new boundary release can ship without a timezonefinder release, and so that a deployment can pin the dataset its answers came from:

pip install "timezonefinder-data==3.2026.3.post1"

The version reads <format>.<year>.<letter>[.postN]: the year and numbered letter name the timezone-boundary-builder release (2026c -> 2026.3), and the major is the binary data format generation. A .postN suffix identifies revised compiled data made from the same upstream release. timezonefinder requires a data version inside the format generation it can read, so an ordinary data update needs no code release while a format change is refused by the resolver instead of at the first lookup.

Releases

• 4.2026.6 - timezone-boundary-builder 2026f, 2026-11-01 - Updated the packaged boundaries to upstream 2026f.
• 4.2026.5 - timezone-boundary-builder 2026e, 2026-10-18 - Updated the packaged boundaries to upstream 2026e and introduced data format 4: a longitude/latitude-aligned grid tree of 0.75° cells, refined into 4×4 blocks where zones meet, replacing the H3 index. Where two zones overlap, the smaller zone now answers in every cell, rather than whichever zone the index cell's vertex counts put first; compared with 3.2026.4 that moves Kafia Kingi and Abyei from Africa/Khartoum to Africa/Juba, the West Bank overlap from Asia/Jerusalem to Asia/Hebron, the Southern Patagonian Ice Field from America/Punta_Arenas to America/Argentina/Rio_Gallegos, the Croatia-Serbia Danube border from Europe/Belgrade to Europe/Zagreb, the Bay of Piran from Europe/Zagreb to Europe/Ljubljana, a strip of the Strait of Juan de Fuca from America/Los_Angeles to America/Vancouver, and slivers of the Sint Maarten and Nova Scotia-New Brunswick borders from America/Marigot to America/Lower_Princes and from America/Halifax to America/Moncton. Upstream 2026e also extends Europe/Madrid over a strip of sea off the Cerbère-Portbou coast that Europe/Paris still covers, which now answers Europe/Madrid.
• 3.2026.4 - timezone-boundary-builder 2026d, 2026-09-21 - Updated the packaged boundaries to upstream 2026d.
• 3.2026.3.post1 - timezone-boundary-builder 2026c, 2026-09-10 - Recompiled shortcut candidates in estimated full-lookup work order.
• 3.2026.3 - timezone-boundary-builder 2026c, 2026-09-02 - Introduced shortcut format 3 with conservative polygon-cell overlap coverage.
• 2.2026.3 - timezone-boundary-builder 2026c, 2026-08-23 - Added latitude-block indexes and packed coordinate payloads.
• 1.2026.3 - timezone-boundary-builder 2026c, 2026-08-18 - First standalone data distribution.

License

The boundary data is licensed under the Open Database License (ODbL), see DATA_LICENSE. The timezonefinder source code is MIT licensed.