Opencals
The booking engine for real service businesses
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Stan

Opencals Storefront API - Build custom booking sites on a booking backend

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The Opencals Storefront API is now public! It's a clean REST API and typed TypeScript SDK for building fully custom booking websites – browse services, check real-time availability (single slots or date ranges for rentals), filter by staff and location, collect Stripe payments, and manage customer accounts. All the hard parts – double-booking, timezones, multi-staff and multi-location logic – are handled server-side.

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Stan
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Hey Product Hunt 👋 I'm Stan, founder of Opencals.

Quick version: Opencals is to service businesses what Shopify is to product businesses – booking, staff, locations, payments, deposits, and customer accounts as real operational infrastructure.
Today we opened our Storefront API + TypeScript SDK so anyone can build their own booking website on top of it.

Here's the thing we kept running into: most service businesses don't want a generic booking page – not even a "customizable" one. They want a site that's actually theirs. So instead of locking everyone into one hosted UI, we made the whole storefront programmable. Start from one of our free open-source templates, or build something completely custom on the API/SDK, you can even vibe-code it with AI in an afternoon. The booking brain (real-time availability, multi-staff, multi-location, deposits, group bookings, rentals, Stripe) is already handled server-side.


How fast it actually is:

  1. Create an account → get a free API key (no card)

  2. You instantly have a full dashboard with every feature working, seed your store with demo data

  3. Clone a template, deploy to Vercel, paste your key

  4. Live in ~5 minutes – the same site as the demo

Links to play with:
🔗 Live demo: https://template-haar.vercel.app
💻 Open-source template (MIT): https://github.com/letsopencals/template-haar
📦 SDK on npm: https://www.npmjs.com/package/@opencals/storefront-sdk
📖 API docs: https://api.opencals.com/docs/storefront

One question I'd love your take on: if you run (or build for) a service business – what industry should we ship the next free template for? Barbershops, tattoo studios, rentals, fitness/classes…? Tell me and I'll build it.

Happy to go deep on anything – the availability model, the SDK, pricing, or what's next on the roadmap :)