JSON API · MCP 2025-11-25

Built for software.
Readable by humans.

The public beta needs no API key. Responses include source records, exact coverage, and calculation traces.

REST endpoints

A small, stable surface.

GET /v1/calendars

Coverage and official source registry.

GET /v1/holidays

Confirmed events for one complete calendar year.

GET /v1/is-business-day

Classification across a calendar intersection.

GET /v1/add-business-days

Forward or backward calculation with trace.

GET /v1/settlement

Versioned regular-way settlement calculation.

Example

curl 'https://provenday.com/v1/settlement?tradeDate=2026-10-09&convention=US_EQUITIES'

The result skips the weekend and the federal holiday on October 12, then returns October 13 with every evaluated date in data.trace.

No-guess contract

{
  "error": {
    "code": "OUT_OF_COVERAGE",
    "message": "XNYS is verified only from 2026-01-01 through 2027-12-31"
  }
}

Model Context Protocol

Connect to https://provenday.com/mcp. It supports initialize, tools/list, and tools/call over Streamable HTTP JSON responses.

Tools: is_business_day, add_business_days, settlement_date, and list_holidays.