Developer infrastructure

Every Panchang answer, explained.

Tithi, nakshatra, muhurat and festivals for any date — each returned with the derivation chain that produced it, not just a value. Change the date below and everything updates from the live API.

connecting
   

connecting…

Festival derived

No festival falls on this date. The panchang below is still computed in full.

Response

The difference

Everyone gives you a date.
We tell you why.

A typical Panchang API

GET /festivals?date=…

Diwali

8 November 2026

A date, and nothing behind it. When a temple committee, an HR department or a reader disputes it, there is nothing to show them — and no way to tell whether the engine was confident or guessing.

TathaAstu

GET /v1/festivals/explain?date=2026-11-08

Diwali

8 November 2026

  1. Amavasya

    Runs 08 Nov 11:28 → 09 Nov 13:01. A tithi is an interval, not a label.

  2. Pradosha

    17:31–19:07. Derived from sunset, so it moves with latitude and season.

  3. 96 minutes of overlap

    Full coverage on 8 Nov. Zero on 9 Nov — Amavasya ended hours earlier.

  4. DIWALI_V2 · v2

    PRADOSHA_VYAPINI. Versioned, never edited in place.

  5. Dharmasindhu · Nirnaya Sindhu

    The shastric authority the rule is drawn from.

  6. Confidence 100

    FULL_KALA_COVERAGE. Deterministic, computed from the overlap fraction.

Every link is in the response body. You can show it to the committee, cite it in the article, or let an agent quote it — read the methodology.

Architecture

One system, eight stages, nothing hidden

This is the actual execution order. Hover any stage to see what it is responsible for.

Swiss EphemerisAstronomyKala evaluationFestival EngineRule versioningVerificationExplainabilityAPI and SDKs

Hover a stage to see what it does. Every one of them is inspectable from the API — the last stage can show you what the others decided.

Trust

Numbers we can point at

Each of these comes from the regression report or the live specification. Where we have not measured something, we publish nothing — including what we still get wrong.

81

REST endpoints

All under one OpenAPI 3.1 contract

152

Automated tests

91% coverage on the festival engine

42/42

Reference checks

Tier A vs DrikPanchang, 1950–2100

2.4 ms

Engine lookup p95

Festival resolution, engine-side

700+

Years of coverage

1700 to 2400, one endpoint

50+

Languages

Phonetic transliteration, not translation

Try it

No key, no signup, no sandbox data

This sends a real request to the production API and shows you exactly what comes back. The full playground adds every endpoint, language switching and the generated code.

Open the full playground
GET /demo/festivals?date=2026-11-08
Press Run to send a real request to the production API. No key required.

Developer platform

Choose how you want to build

A REST API is the starting point, not the whole product. Everything below will be generated from one OpenAPI document — and nothing appears as available until you can actually install it.

Available now

REST APIAvailable81 endpoints in production, every response carrying a confidence score and engine version.OpenAPI 3.1AvailableThe machine-readable contract every client is generated from — with named operation ids, a declared security scheme and documented error responses.Postman / InsomniaAvailableImport the OpenAPI URL directly — no separate collection to fall out of date.Live playgroundAvailableReal requests against production, no account required.WebhooksAvailableHMAC-signed delivery with backoff and explicit idempotency semantics.Python SDKAvailablev0.1.0 — 79 methods across 19 namespaces, generated from the spec. Retries, distinct error types, rate-limit surface. 30 tests. Wheel builds. Not on PyPI yet, so there is no install command.TypeScript SDKAvailablev0.1.0 — the same 79 methods and namespaces as Python, enforced by a parity check in CI. ESM and CommonJS, full type declarations. 29 tests. Not on npm yet.MCP serverAvailablev0.1.0 — six tools over stdio JSON-RPC, including explain_festival so an agent can cite a rule and version rather than assert a date. 20 tests. Built on the TypeScript SDK.CLIAvailableTerminal access to panchang, festivals, muhurat and explain. Wraps the TypeScript SDK — no second HTTP implementation.React widgetsAvailableDrop-in components for panchang, festivals and muhurat, consuming the TypeScript SDK.AI tool definitionsAvailableOne shared adapter exposing six tools to OpenAI, Anthropic, Gemini and LangChain — a single registry rather than four hand-maintained copies.VS Code extensionAvailablePanchang and festival lookups without leaving the editor. Built and tested; not yet on the Marketplace.

On the roadmap

GitHub ActionBuilt · not publishedCalendar checks in CI, reporting rather than blocking on pull requests.
Go, Java and C# SDKsDeferred to v0.2Deferred to v0.2. Generating them is straightforward from the same spec; we will not ship a client we cannot compile and test, and those toolchains are not yet in our build.

Nothing here carries an install command, including the items marked built — those are code-complete and tested but not yet on npm or PyPI. Each will be announced in the changelog the day it resolves on its registry, and not before.

Pricing

Find yourself on this list

Confidence scores and the engine envelope are on every plan, including Free. You should never have to pay to find out how certain an answer is.

You are evaluating

Prototyping a feature and want to see whether the dates hold up.

You are shipping

A side project or MVP in front of real users, needing muhurat and explainability.

You are in production

Serving real traffic, precomputing ahead, and you need an uptime commitment.

You are scaling

A growing SaaS with sustained traffic and a support commitment to your own customers.

You need a contract

A city we do not cover, a rule pack we have not authored, or procurement.

Build on a calendar that
shows its work.

500 requests a day on the Free plan, no card required. Confidence scores and the engine envelope are included on every tier.