Cal.com Teardown — Open-Source Calendly Alternative ($10M+ ARR + Cal AI $50M ARR)
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Cal.com Teardown — Stripe for Time
Last updated: 2026-05-16 · Researched via cal.com + GitHub + Crunchbase/PitchBook/Tracxn/Latka + 2026-04 closed-source announcement reports
TL;DR
"Stripe for time" — open-source Calendly alternative, started 2021, 2024 $5.1M revenue / 20K paying customers, ~$200M valuation, $32.4M funding (OSS Capital + Seven Seven Six + Obvious Ventures), 42.5K GitHub stars. 2026-04 closed main repo, went source-available, only Cal.diy community version remains (MIT, gated). Complete "open-source draw attention → cloud hosting monetization → commercial version close" playbook, 0 to $5M ARR in 3 years. Cal.ai (AI Phone Agent) is 2024-2025 differentiator: $30M ARR Dec 2025, $50M ARR Mar 2026. Cal.ai is the real revenue story, not scheduling base.
Basic Info
| Item | Detail |
|---|---|
| Website | cal.com |
| Positioning | OSS scheduling infrastructure / Stripe for time |
| Founders | Peer Richelsen (CEO ex-OnDeck Head of Product) + Bailey Pumfleet (Co-CEO, originally Calendso subscriber) + David Eriksson + Cyrielle Simeone + Ben Murphy |
| Founded | 2021-04-30 (Calendso) |
| Employees | 31 (2026, was 21 in 2023) |
| Funding | $32.4M total — Seed $7.4M (OSS Capital + Joseph Jacks) + Series A $25M (Seven Seven Six + Obvious Ventures) |
| 2024 revenue | $5.1M revenue / 20K paying customers (Latka) |
| Cal AI 2026-03 ARR | $50M ARR (voice agent single product) |
| GitHub | 42.5K stars / 13.2K forks / Next.js + Prisma + Postgres + tRPC + TypeScript 95.8% |
| License | AGPL-3.0 (2021-2026/03) → source-available, Cal.diy fork MIT (2026/04+) |
Core Features
- Basic scheduling — booking link, custom availability, daily/weekly limits, buffers, collective/round-robin
- White-label + embed — iframe, custom domain, subdomain
- 65+ languages
- Cal Video — built-in video conferencing
- Routing Forms — form → routing to different teams
- Workflow Automations — booking triggers SMS/email/Slack/Zapier
- 100+ integrations — Salesforce/HubSpot/Stripe/PayPal/Google Cal/Outlook/iCloud
- Cal Atoms — SDK to embed scheduling in 3rd-party products (B2B2C channel)
- Cal.ai (AI Phone Agent) — user calls in, AI auto-takes booking + answers FAQ + transfers to human. 2024-2025 key differentiator, $50M ARR
- Self-host — Docker/Railway/Vercel/Render (closed-source post 2026/04 functionality limited)
- Calendly import — one-click migration
Pricing
| Tier | Price (USD) | Users | Features | AI Phone Agent |
|---|---|---|---|---|
| Free | $0 | 1 | Unlimited event types + Stripe/PayPal + 100+ integrations + Calendly import | ❌ |
| Teams | $12/user/mo (annual 25% off) | Team | Round-robin / Collective / Routing Forms / Booking Analytics | ❌ |
| Organizations | $28/user/mo | Unlimited sub-teams |