CalendarForge API
Version 0.1.0 · Calendar dates use ISO YYYY-MM-DD civil-date strings; they are not timestamps and are never shifted by local time zones.
Open the machine-readable OpenAPI 3.1 schema · Check service health
Public date endpoints
GET /api/v1/health— runtime and database-configuration status.GET /api/v1/calendar?year=2026&month=10&weekStartsOn=monday— month grid, ISO weeks and observed federal holidays.GET /api/v1/business-days?start=2026-10-01&end=2026-10-31— inclusive weekday count, excluding weekends and observed federal holidays.GET /api/v1/business-days?start=2026-10-01&amount=10— add or subtract signed business days.GET /api/v1/fiscal/445?year=2026— retail 4-4-5 period boundaries.GET /api/v1/exports/ics?year=2026— downloadable observed US federal holiday calendar.
PostgreSQL project endpoints
These routes require Authorization: Bearer YOUR_CALENDARFORGE_API_TOKEN. Configure DATABASE_URL and a long, unique CALENDARFORGE_API_TOKEN. The table calendar_projects is initialized on the first authorized request. Projects are private to that shared token; this is a single-operator API, not multi-user authentication or workspace isolation.
GET /api/v1/projects— list up to 100 projects, newest updates first.POST /api/v1/projects— create a project with a name and year; settings and events are optional JSON.GET /api/v1/projects/{id}— read one project.PATCH /api/v1/projects/{id}— update its name, year, settings, or events.DELETE /api/v1/projects/{id}— delete one project.
The request body for project creation includes a name (1–120 characters) and a year (1–9998); settings and event objects are optional. Send the bearer token over HTTPS and never expose it in browser code.
Demo data and privacy
Events entered in this public browser demo are saved in that browser's local storage. They do not use the PostgreSQL project API and are not shared with other visitors. Do not enter private calendar data into the public demo. For a persistent project API, deploy your own instance and protect its bearer token.
Calendar references
CalendarForge is independently implemented and does not call Make a Calendar private services. Complementary resources from the maker of Make a Calendar: browse printable monthly calendars, business-day calculations, 4-4-5 fiscal calendars, and the online iCalendar generator.