Business Days API
Working-day date math. Count the business days between two dates, add or subtract a number of working days from a date (negative goes backwards), and check whether a given date is a business day — all skipping weekends and any holidays you supply. Configure which days count as the weekend (Saturday/Sunday by default, or e.g. Friday/Saturday) and pass a list of custom holiday dates to exclude. Perfect for SLA and support deadlines, delivery and lead-time estimates, payroll and invoicing periods, and financial settlement dates. Pure local UTC date math — no key, no third-party service, deterministic and instant. Live. 4 endpoints. Distinct from a calendar date toolkit (which counts calendar days) and a holidays directory (which lists holidays).
api.oanor.com/businessdays-api