Date math that survives contact with the real world
“Three business days” means something different in Riyadh, Kathmandu, and New York. Chronos gives you one endpoint for settlement dates, SLA deadlines, and payroll cutoffs — correct across 250+ countries, 1,500+ subdivisions, and financial-market calendars.
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Why this exists
Every team eventually writes AddBusinessDays(). It works until a trade
settles across Good Friday, an SLA deadline lands on a substitute bank holiday that
only exists because Christmas fell on a Saturday, or a delivery promise assumes a
Saturday–Sunday weekend in a country that works Sundays. Holiday data APIs give you
raw lists; the bugs live in the calculation. Chronos does the calculation.
What you get
/v1/add
Add or subtract N business days from a date — T+2 settlement, “respond within 5 working days”, payment terms./v1/count
Business days between two dates, inclusive, sign-symmetric. SLAs, payroll periods, delivery windows./v1/check
Is this date a working day here? Weekend, holiday, and next-business-day in one call./v1/holidays
The underlying holiday calendar for any region and range, when you do need the raw list.Example
curl "https://api.example.com/v1/add?region=XNYS&start=2027-03-25&days=2" \
-H "X-Api-Key: $KEY"
{"region":"XNYS","start":"2027-03-25","days":2,"result":"2027-03-30"}March 26, 2027 is Good Friday — NYSE closed, most US offices open. T+2 lands Tuesday, not Monday. That is the sort of thing you no longer have to know.
Honest limits
Coverage is 2020–2035, refreshed continuously from open-source calendar data and verified against multiple sources. Requests outside the range return an explicit error rather than a silently wrong answer. If we do not have a region, we say so.