About DayAPI

DayAPI is a single-purpose API: holiday and business-day answers checked carefully enough to sit inside a payroll run.

It is built by the team behind KINGAI.WORK, and it started from a repeated failure in client work. Delivery and payment dates kept being calculated on the wrong country's calendar, and off-the-shelf holiday lists disagreed with each other often enough that checking them by hand became the job. DayAPI is that checking, packaged as JSON.

Current status

v1 is live as a read-only dataset API for 2026, covering 12 countries and 108 holiday entries. The status page lists every endpoint that answers. Paid tiers and keys come later, and the pricing page keeps them labelled planned until they do.