Is the exchange in its core session at this instant? (NYSE holidays and 13:00 early closes, or a caller calendar)

$0.005 USDC per call · Business, finance and compliance · POST /api/v1/market-session · Id market-session

For up to 50 caller-supplied instants, reports whether the NYSE core session (09:30-16:00 America/New_York, 13:00 on early-close days) is open, the reason when closed (weekend, named holiday, before open, after close), that day's open and close instants and the next open; or the same for a caller venue (zone, open, close, holidays, early closes). NYSE data is a dated snapshot of nyse.com covering 2026-2028; any instant outside it is `unsupported`. It does not cover pre-market, extended hours, auctions, other exchanges' calendars, halts or unscheduled closures, and never reads the clock: pass the instant you care about.

What you get

An order or a data pull timed for a US holiday or the 13:00 half-day fails or returns stale data.

Call it

Send the JSON body below to https://agents.writerslogic.com/api/v1/market-session. An unpaid request answers 402 with the price and how to pay; a request that fails with a 5xx status is not charged.

curl -i -X POST https://agents.writerslogic.com/api/v1/market-session \
  -H 'content-type: application/json' \
  -d '{"venue":"nyse","instants":["2026-11-27T17:30:00Z","2026-11-27T19:30:00Z","2026-07-03T15:00:00Z"]}'

Input

Field	Type	Required	Description
`venue`	string; one of "nyse", "caller"	yes
`instants`	array<string; length 0..36>; max 50 items	yes	RFC 3339 timestamps with Z or offset.
`expect`	string; one of "open", "closed"	no	If given, status is fail for any instant whose state differs.
`timeZone`	string; length 0..64	no	venue caller only.
`open`	string; length 0..5	no	venue caller only, local HH:MM.
`close`	string; length 0..5	no	venue caller only, local HH:MM, after open.
`holidays`	array<string; length 0..10>; max 400 items	no	Extra non-business dates YYYY-MM-DD (company closures, a calendar we do not carry).
`weekend`	array<integer; 0..6>; max 6 items	no	Non-business weekdays, 0=Sunday..6=Saturday. Default [0, 6]; use [5, 6] for a Friday/Saturday weekend.
`earlyCloses`	array<object>; max 100 items	no	venue caller only.

Example request body

{
  "venue": "nyse",
  "instants": [
    "2026-11-27T17:30:00Z",
    "2026-11-27T19:30:00Z",
    "2026-07-03T15:00:00Z"
  ]
}

Result

The response is { "data": ..., "_provenance": ... }. data carries these fields; _provenance is a signed W3C Verifiable Credential with a C2PA-style manifest, checked free at POST /api/v1/verify-provenance.

Field	Type	Required	Description
`status`	string; one of "pass", "fail", "unknown", "unsupported"	no	pass: every rule held. fail: a rule was violated (see witnesses). unknown: the input lacks the evidence to decide. unsupported: outside what this engine covers. Missing evidence is never a pass.
`items`	array<object>	no
`reason`	string	no
`witnesses`	array<object>	no
`versions`	object	no	Every semantic dependency of this answer (engine, tables and their as-of dates, tokenizer, calendar, rounding profile).
`limits`	array<string>	no
`deterministic`	boolean	no	Always true: pure code, no model.

Pay and connect

Available through: x402 (USDC on Base), MCP. MCP clients reach it through the calendar-deadline-kit package.

Machine-readable

This agent as JSON (schemas, example, OpenAPI operation)
Free signed sample response
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