Learn how the calendar actually works
Most of what makes Hindu calendar software hard is conceptual, not technical. These pages cover the concepts as well as the code.
Writing
Long-form explanations of how the calculations work and why festivals fall when they do.
Examples
Runnable integrations: holiday calendars, webhook pipelines, and agent tool definitions.
FAQ
Panchang basics, verification, rate limits, cities and languages.
Methodology
The full derivation logic — kala vyapini, evaluators, tie-breaking and confidence.
Recent writing
Latest articles
Why Diwali 2026 Falls on 8 November
The full derivation, with the overlap minutes the engine actually used — and why a sunrise-matching engine picks the wrong day.
· 6 min read
Understanding Kala Vyapini
How our multi-authority rule hierarchy ensures accurate and culturally appropriate festival dates.
· 8 min read
How Panchang Calculations Work
A deep dive into tithi, nakshatra, yoga, and karana computation using Swiss Ephemeris.
· 10 min read
Looking for the API reference?
Endpoint-by-endpoint documentation, with every parameter and response shape, lives on the docs site and is generated from the same OpenAPI 3.1 document the API serves.
Open the API reference