Missed the latest GitHub check; these facts may be older.
Overview
Cal.diy is a booking and scheduling web app built on Next.js, tRPC, Prisma and PostgreSQL. It is a fork of Cal.com with the enterprise code removed (Teams, Organizations, Insights, Workflows, SSO/SAML), so no license key is needed. It runs through Docker Compose or from source with yarn, and the README recommends it only for personal, non-production use.
Who it is for: Individuals self-hosting a personal scheduling and booking page
Strengths
Whole codebase is MIT, with no enterprise edition or license key
Docker Compose stack bundles the web app, Postgres and Prisma Studio
`yarn dx` starts a local Postgres and seeds test users for development
Calendar integrations can be added after setup from Settings > Integrations
Weaknesses
README advises personal, non-production use only
Teams, Organizations, Workflows and SSO/SAML are removed
No hosted version; you run and secure the server yourself
Docker source build needs a live database and DOCKER_BUILDKIT=0