Regional business-day & holiday API
Business-day math and public holidays by country and region (US states, German Länder) — the coverage national-only free sources miss. Free tier, no card.
curl "https://gridcal-api.aly-ventures.workers.dev/v1/is-business-day?country=US®ion=CA&date=2025-11-28"
# { "business_day": false, "holiday": "Day after Thanksgiving" }