## Startup showcase (1-1 of 1)

### Cal.com
Open-source scheduling for people and teams

49,459 GitHub stars (calcom/cal.diy, MIT, 2026-10-28) · App Store 4.9/5 from 216 ratings (2026-10-28)

Website + app · Productivity · by Cal.com, Inc. · launched 2021-03-22. https://cal.com

- Frontend: Next.js
- Backend: Prisma
- Database: PostgreSQL, Upstash (`upstash`, priced)
- Sign-in: Auth.js (NextAuth)
- Hosting: Vercel (`vercel`, priced)
- Payments: Stripe (`stripe`, priced)
- Email: SendGrid (`sendgrid`, priced)
- Other: Twilio (`twilio`, priced), Intercom (`intercom`)
- Analytics: PostHog (`posthog`, priced)
- Monitoring: Sentry (`sentry`, priced)

Most used: Auth.js (NextAuth) (1), Intercom (1), Next.js (1), PostgreSQL (1), PostHog (1), Prisma (1), SendGrid (1), Sentry (1), Stripe (1), Twilio (1), Upstash (1), Vercel (1).

**Caveats (show these word for word)**
- Stacks are read from each product's public code (manifests and environment templates) on the date shown; a service listed there may be optional or used only by the hosted version. GitHub and App Store figures are as read on their checked_at date.

Confidence: medium.

Use estimate_cost or audit_stack with the priced vendor ids to see what a stack like this costs.