Non-Working Days vs Non-Working Days

icsdb is an open-data repository of pre-built .ics calendar files enumerating official non-working days for France (and its overseas territories), Belgium, Germany, Ireland, Switzerland, the UK's home nations, and the US, maintained on GitHub rather than served through a query API. Consumers fetch the raw .ics files directly off raw.githubusercontent.com (which serves them with open CORS) and import them into any calendar tool or icalendar-parsing library; there's no key, rate limit, or cost, but the project itself has had no commits since 2020.

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.