Business days, working hours, and holidays over one REST call.
Public preview — 247 countries at national level, each adjudicated against authoritative sources with a published verification status · US covered in depth (federal + all 57 states & territories, externally audited).
Timezone- and DST-aware working hours, versioned answers, and correct observed days.
"Respond within 8 business hours" — computed on zoned wall-clock time, so spring-forward gaps, fall-back doubled hours, and 30-minute-offset zones are handled correctly, not by adding seconds to a UTC instant.
Every answer is pinned to a dataset version and a tzdata/ICU version, surfaced via X-Dataset-Version and X-Tzdata-Version headers and a meta block. Reproducible and auditable for settlement dates, statutory deadlines, and SLAs.
Observed and substitute days are correct (July 4 on a Saturday resolves to the Friday observed day). US subdivisions resolve regional holidays — California observes Cesar Chavez Day but not Columbus Day.
Everything below is live — click any of it and check.
Business days, working hours, holidays — every example on this page runs against the production API, keyless.
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Every country: national holidays, weekend definition (Fri–Sat, Sat-only, …) and primary timezone. US adds all 57 ISO 3166-2 subdivisions with their own exceptions (try US-CA).
X-Dataset-Version / X-Tzdata-Version on every response; pin ?dataset=2026.2 and the answer is frozen forever — old versions stay servable.
The exact frozen artifact the API serves, content-hashed and MIT-derived — verify it yourself. If we vanish, you keep the data.
The full contract, tested in CI to match the implementation exactly. Plus a public methodology and live status.
On the roadmap. If one of these is what you'd pay for, tell us.
Regional holidays for more countries — each gets the US treatment (self-contained per-jurisdiction sets, externally cross-checked) before it ships.
Markets like NYSE and LSE.
Your own holidays, per location.
Alerts when a dataset update changes an answer you rely on.
Typed clients from the OpenAPI spec.
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Get my key →Instant and self-serve — no card, no approval step. 120 requests/min. We'll also send you the launch note and product updates about Datewise (privacy) — no other mail.