Dateline API

Business-day math and public holidays for 200+ countries and their states. Add working days to a deadline, count business days between dates, and check whether any date is a working day.

Examples

• Is Dec 25 a business day in the US?
  /api/v1/is-business-day?country=US&date=2026-12-25
• 10 business days after Dec 18 (UK)
  /api/v1/add-business-days?country=GB&date=2026-12-18&days=10
• Business days in December (Florida)
  /api/v1/business-days-between?country=US&state=FL&start=2026-12-01&end=2026-12-31
• Germany's 2027 holidays
  /api/v1/holidays?country=DE&year=2027
• All supported countries
  /api/v1/countries