Settlement / value date
T+n settlement across one or more national statutory calendars intersected, with a per-day trail, each calendar's basis and source, and the market cycle cited to its primary instrument where we hold one. Refuses rather than guessing a cycle it cannot cite.
This endpoint takes a POST, because it computes an answer from values you supply — there is nothing to fetch at this URL. You are seeing this page because your browser asked for HTML; an API client gets a 405 with the same information as JSON.
Call it
curl -X POST https://usaref.dev/v1/answers/settlement-date \
-H 'content-type: application/json' \
-d '{"trade_date":"2026-07-30","calendars":["za"],"business_days":3}'Body fields: trade_date, business_days, calendars, market, instrument_class, mode
Paid per call over x402 (USDC on Base) — no key, no signup. Invalid input and questions we cannot answer well are refused free, before the payment gate: you never pay to fail.
What sits behind the answer
Every computed answer is arithmetic on cited reference data. The underlying values each carry their official source, an effective date and a last-verified date, and each declares how it was obtained — see the country pages and source provenance. Results are labelled basis: "computed" and are not tax, legal or financial advice.
Free to inspect
/catalog — every country and series held · /llms.txt — endpoints, prices and example bodies · /openapi.json · /accuracy — where reference data is wrong, including ours