📅 CalendarTunnel
CalendarTunnel is a multi-user SaaS calendar sync service that mirrors events across Google, Microsoft, Zoho, iCloud, and ICS feed calendars as busy blocks to prevent double bookings.
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Achievements
Launched CalendarTunnel
Shipped the full SaaS product including OAuth integrations for Google, Microsoft, Zoho, iCloud CalDAV, and ICS feeds with a Stripe billing lifecycle.
𝗦𝗶𝘁𝘂𝗮𝘁𝗶𝗼𝗻
Professionals managing multiple calendar platforms — Google, Microsoft, Zoho, iCloud — face constant double-booking risk since there is no native cross-platform busy-block sync. Existing solutions are either limited to two platforms or require manual intervention.
𝗧𝗮𝘀𝗸
Build a privacy-first SaaS platform that automatically mirrors events as busy blocks across all major calendar providers in real time, supporting multiple users, multiple calendars per account, and a full billing lifecycle.
𝗔𝗰𝘁𝗶𝗼𝗻
Architected a TypeScript monorepo (pnpm + Turborepo) with a Hono API server, a background sync worker, and a React 19 + React Router v7 frontend.
Implemented OAuth 2.0 flows for Google, Microsoft, and Zoho; credential-based CalDAV connect for iCloud; and SSRF-protected ICS feed ingestion.
Built a hybrid sync engine combining webhook push notifications (Google, Microsoft) with a polling fallback for all providers, with per-account locking and debouncing.
Designed a privacy-first architecture: no event content is stored or logged — change detection uses SHA-256 hashes, and all tokens are encrypted with AES-256-GCM with key rotation support.
Shipped configurable event transformers (title masking, status prefixes) and filters (declined, all-day, free, regex, time window, work status, color, category) stored as JSONB per account.
Integrated Stripe Checkout and Customer Portal for three tiered plans (Starter, Growth, Pro) with a 7-day free trial and automated subscription lifecycle via webhooks.
Deployed via Docker Compose on Hetzner with Caddy for automatic TLS, static asset serving, SPA fallback, and security headers; optional Cloudflare CDN with cache purge on deploy.
Shipped a fully internationalized landing page in 25 languages with Framer Motion animations, prerendered static HTML, and auto-generated hreflang sitemaps.
𝗥𝗲𝘀𝘂𝗹𝘁
CalendarTunnel provides seamless, real-time busy-block mirroring across all major calendar platforms with a privacy-first design, full billing lifecycle, and a polished multilingual frontend — all running on a cost-efficient single-server Docker stack.