fatcalendar documentation

Developer and agent documentation for the fatcalendar REST API, MCP server, SDK and agent protocols.

Choose an interface

InterfaceUse it whenEntry point
REST APIScripts, apps, backendshttps://fatcalendar.com/api/v1 and openapi.json
MCP serverClaude, Cursor, ChatGPT and other AI assistantshttps://fatcalendar.com/mcp
SDKTypeScript / React Native@fatcalendar/core
Agent guideAutonomous agents and crawlersAGENTS.md, llms.txt

All interfaces are free, need no API key and return the same data.

Quick start

curl 'https://fatcalendar.com/api/v1/calendar/day?tradition=telugu&lang=en&place=Hyderabad&date=2026-11-08'

Concepts

  • tradition selects the calendar system (gregorian, telugu, tamil, kannada, malayalam, marathi, gujarati, punjabi, bengali, hindi, muslim, christian). lang selects the display language (en, te, ta, kn, ml, mr, gu, pa, bn, hi, ur). They are independent.
  • variant optionally selects a sub-variant of the tradition.
  • Location is lat + lon + tz, or place free text, or inferred from the request.
  • Dates are civil dates YYYY-MM-DD in the location's time zone.

Machine-readable index