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calcom/cal.diy

Scheduling infrastructure for absolutely everyone.

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What it does

Cal.diy is a self-hosted, open-source scheduling tool that lets individuals and teams manage bookings, appointments, and availability — essentially a free version of Calendly you run on your own servers. It handles all the plumbing of scheduling infrastructure, so builders can embed or customize meeting-booking capabilities without relying on a third-party service.

Why it matters

With nearly 42,000 stars and over 900 contributors, this project signals strong market demand for scheduling infrastructure that teams can own and customize rather than rent — a key consideration for products where booking flows are core to the user experience. Founders building in healthcare, recruiting, sales, or any appointment-driven vertical can use this as a foundation instead of paying per-seat SaaS fees or building from scratch.

54Hot

Gaining traction — heating up

Stars
41.4k
Forks
12.8k
Contributors
935
Language
TypeScript

Score updated Apr 18, 2026

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