Namedays Calendar vs Non-Working Days

This API looks up which name(s) are celebrated on a given calendar date — or which date a given name falls on — across roughly 40 countries' nameday traditions, via a documented OpenAPI v2 surface (/today, /tomorrow, /yesterday, /getdate) served as JSON. It's a personal open project by its maintainer (Michal Abaline) with no signup, no API key, and no rate limiting, positioned as a lighter keyless alternative to older nameday lookup services.

isdayoff.ru answers one narrow question extremely cheaply: for a date or date range, is it a working day, a weekend, or an official non-working holiday. Responses are bare digit strings (0/1 per day, or 2 for a shortened day) rather than JSON, which keeps payloads tiny for the batch/range endpoint. It documents Russia, Belarus, Ukraine, Kazakhstan, and the US as supported country codes, but live probes this run found only Russia (the default), Belarus, and Kazakhstan return genuinely varying data — the Ukraine and US codes are accepted (HTTP 200) but answered every single day of several different months with a flat, undifferentiated "0". It's free, keyless, and has no published rate limit, built for production-calendar bookkeeping rather than general holiday metadata.