@nandan-varma/calendar-sdk-microsoft

calendar-sdk

One TypeScript API for Google Calendar, Microsoft Graph (Outlook), and CalDAV/iCloud — events, calendars, availability, incremental sync, and webhook subscriptions, without vendoring three different SDKs into your app.

An open alternative to paid unified-calendar APIs: bring your own OAuth credentials, keep your users' tokens in your own storage.

Packages

Package	What it is
@nandan-varma/calendar-sdk	Core: unified services (accounts, calendars, events, availability, subscriptions, sync), storage + hooks + retrying transport
@nandan-varma/calendar-sdk-google	Google Calendar provider adapter
@nandan-varma/calendar-sdk-microsoft	Microsoft Graph calendar provider adapter
@nandan-varma/calendar-sdk-caldav	CalDAV provider adapter (iCloud, Fastmail, Nextcloud, …)
@nandan-varma/calendar-sdk-mock	In-memory provider for tests and examples — no credentials or network calls
@nandan-varma/calendar-sdk-auth	OAuth flow, token refresh, and encrypted token-set helpers

Install

npm install @nandan-varma/calendar-sdk @nandan-varma/calendar-sdk-google

Quick start

import { createCalendarSdk } from "@nandan-varma/calendar-sdk";
import { createGoogleProvider } from "@nandan-varma/calendar-sdk-google";

const sdk = createCalendarSdk({
  providers: [
    createGoogleProvider({
      clientId: process.env.GOOGLE_CLIENT_ID!,
      clientSecret: process.env.GOOGLE_CLIENT_SECRET!,
    }),
  ],
  // storage defaults to in-memory; plug in your database via StorageAdapter
});

// Connect an account (tokens from your OAuth callback)
const account = await sdk.accounts.connect("google", {
  authInput: { accessToken, refreshToken },
});

// Same API for every provider from here on
const calendars = await sdk.calendars.list(account.id);
const events = await sdk.events.list(calendars[0].id, {
  timeMin: new Date(),
  timeMax: new Date(Date.now() + 7 * 86400_000),
});

await sdk.events.create(calendars[0].id, {
  title: "Coffee",
  start: { dateTime: "2026-08-01T10:00:00Z", timezone: "UTC" },
  end: { dateTime: "2026-08-01T10:30:00Z", timezone: "UTC" },
});

// Free/busy across an account's calendars
const freeBusy = await sdk.availability.freeBusy(account.id, {
  timeMin: new Date(),
  timeMax: new Date(Date.now() + 86400_000),
  calendars: [calendars[0].providerId],
});

Swap createGoogleProvider for createMicrosoftProvider or createCalDavProvider and the rest of your code stays identical. A single SDK instance can register more than one provider at once — just add another entry to providers.

Want to try it with zero setup? examples/quickstart.ts runs this same flow against @nandan-varma/calendar-sdk-mock — no credentials or network access needed:

pnpm install
pnpm --filter @nandan-varma/calendar-sdk-examples quickstart

OAuth helper

import { createAuthFlow } from "@nandan-varma/calendar-sdk-auth";

const flow = createAuthFlow({
  provider: "google",
  clientId: process.env.GOOGLE_CLIENT_ID!,
  clientSecret: process.env.GOOGLE_CLIENT_SECRET!,
  redirectUri: "https://app.example.com/oauth/callback",
  scopes: ["https://www.googleapis.com/auth/calendar"],
});

const authorizationUrl = flow.getAuthorizationUrl(); // send the user here
const tokens = await flow.exchangeCode(codeFromCallback); // then call sdk.accounts.connect(...) with these tokens
// flow.refreshToken(...) / flow.revokeToken(...) are also available once you have a stored token

See examples/google-oauth.ts for the full connect flow wired up behind a small HTTP server.

Testing your integration

@nandan-varma/calendar-sdk-mock is a fully in-memory ProviderAdapter — no network calls, deterministic — so you can exercise your own code against the whole SDK surface without live credentials:

import { createCalendarSdk } from "@nandan-varma/calendar-sdk";
import { createMockProvider } from "@nandan-varma/calendar-sdk-mock";

const sdk = createCalendarSdk({ providers: [createMockProvider()] });

Design

• Providers are adapters. The core knows nothing about any vendor API; each provider implements one ProviderAdapter interface. Adding a provider does not touch the core.
• Storage is pluggable. Accounts and token sets live behind a StorageAdapter; the default is in-memory, production apps supply their own (Postgres, Redis, …).
• Sync is incremental. sdk.sync uses Google syncToken / Graph delta queries where available.
• Transport is resilient. Built-in retry with backoff for rate limits and transient failures; pass fetch/retryOptions to a provider factory (e.g. createGoogleProvider({ ..., fetch, retryOptions })) to override its defaults.
• Hooks let you observe/instrument every operation.

See SPEC.md for the full v1 design rationale.

Documentation

Comprehensive docs (guides for every service, provider setup, storage, sync, webhooks, and full reference) are published at https://nandan-varma.github.io/calendar-sdk/ and live in docs/, built with Astro Starlight:

pnpm --filter @nandan-varma/calendar-sdk-docs dev    # local docs at http://localhost:4321
pnpm --filter @nandan-varma/calendar-sdk-docs build  # static site in docs/dist

Development

pnpm install
pnpm build       # build all packages (including the docs site)
pnpm test        # run all test suites
pnpm typecheck
pnpm lint

License

MIT