caldays vs Hebrew Calendar

Caldays provides free public holiday data for 206 countries in JSON format, plus long-weekend calculations and a world clock endpoint. Anonymous use is capped at 10,000 requests per day; a metered API key raises the limit for higher-volume needs. The holiday data carries a CC BY 4.0 licence, so users must credit Caldays in their app.

Hebcal converts between Gregorian and Hebrew dates and computes Shabbat start/end times, holiday dates, Torah readings, and the Daf Yomi study cycle for any location, driven by the same open-source engine (@hebcal/core) that runs the hebcal.com website. Every endpoint is keyless JSON (or RSS/iCal on other routes) under a Creative Commons Attribution 4.0 license, so results can be reused commercially as long as Hebcal is credited. It's rate-limited to keep the free service polite — no more than 90 requests per 10-second window — and the once-http-only backend now serves over HTTPS as well.