What is cal.diy?

Cal.diy is a fully open-source, self-hostable appointment scheduling platform, the kind of tool that lets you share a booking link so other people can schedule time with you based on your real availability, without the back-and-forth of finding a mutual time slot. It is a fork of Cal.com, which is a commercial scheduling product, but with all proprietary enterprise features removed so the entire codebase is available under the MIT license with no strings attached. The way it works is that you set up your calendar availability and create different event types, for example, a 30-minute consultation or a 60-minute meeting, then share a personal booking page link. People visiting that link see only the times you are free (based on your connected calendar), pick a slot, and a calendar invite is automatically created for both parties. It integrates with Google Calendar, Outlook, and video conferencing tools to insert meeting links automatically. Cal.diy is distinct from the paid Cal.com hosted service in that you run it entirely on your own server or infrastructure. There is no hosted version of Cal.diy, you clone the repository, provision a PostgreSQL database, and deploy it yourself. The README explicitly warns that this requires server administration experience and is recommended for personal, non-production use rather than high-stakes business deployments. Someone would use Cal.diy when they want the functionality of tools like Calendly but want to own their data, avoid subscription fees, and run the software under their own control. The tech stack is TypeScript with Next.js for the web framework, tRPC for type-safe API communication between frontend and backend, Prisma as the database ORM against a PostgreSQL database, Tailwind CSS for styling, and NextAuth for authentication.