Getting Started

JDay is a business-day computation API built for AI agents. It handles weekends, public holidays, observed dates, and regional calendars across 20 countries.

Quick Start

Make your first API call:

curl -X GET "https://jday-api.jday.workers.dev/v1/is-business-day?date=2026-04-03&country=ZA" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Accept: application/json"

Response:

{
  "date": "2026-04-03",
  "country": "ZA",
  "region": null,
  "is_business_day": false,
  "reason": "public_holiday",
  "holidays": [
    {
      "date": "2026-04-03",
      "official_date": null,
      "name": "Good Friday",
      "local_name": null,
      "type": "public",
      "date_accuracy": "exact"
    }
  ],
  "timezone": "Africa/Johannesburg",
  "next_business_day": "2026-04-07",
  "previous_business_day": "2026-04-02"
}

What JDay Does

• Is this a business day? Check any date against a country's calendar.
• Add business days. Compute a future or past date, skipping weekends and holidays.
• Count business days. Get the number of working days between two dates.
• List holidays. Retrieve all holidays for a country and year.
• List countries. See all supported countries and their metadata.

Key Facts

• 20 countries at launch, with regional holiday support for AU, CA, DE, GB, and US.
• Date range: 2025-01-01 through 2027-12-31.
• Authentication: Authorization: Bearer <api_key> on all endpoints.
• Deterministic: Same input always produces the same output.
• Agent-first: Structured JSON responses designed for tool calling.