Cal.diy

Cal.diy is the community-driven, MIT-licensed scheduling platform — a fork of Cal.com with all enterprise/commercial code removed. It is a self-hosted Next.js application backed by PostgreSQL, designed for individuals and self-hosters who want full control over their scheduling infrastructure without proprietary "Open Core" constraints.

The project lives at github.com/calcom/cal.com (the calcom/cal.com repository hosts the Cal.diy codebase per the current README.md). It powers user signups, event-type configuration, calendar federation, slot computation, bookings, video calls, embeds, and over 100 integrations with calendars, conferencing tools, payment providers, CRMs, and analytics services.

What this codebase does

• Schedules meetings — public booking pages, group bookings, round-robin assignment, recurring events, managed event types, and seat-based events. The EventType Prisma model in packages/prisma/schema.prisma is the single source of truth for what an organizer offers.
• Federates calendars — pulls free/busy from Google, Microsoft 365 / Exchange, Apple, Lark, Feishu, CalDAV, and ICS feeds, and writes back confirmed events to chosen destination calendars.
• Hosts video calls — first-party Daily.co video (packages/app-store/dailyvideo) plus Zoom, Google Meet, Office 365 Video, Webex, Jitsi, and ~25 other conferencing apps.
• Exposes APIs — a Next.js + tRPC layer for the web app, plus a separate NestJS service in apps/api/v2 that powers the REST API documented at apps/api/docs/.
• Provides embeds and SDK atoms — JavaScript snippet, React component, and Web Components in packages/embeds/*, plus high-level "atom" React components for the Cal.com Platform SDK in packages/platform/atoms.
• Ships an App Store — over 100 third-party integrations live in packages/app-store/*, each wired in via packages/app-store-cli.

Tech stack at a glance

• Language: TypeScript (strict). 3,800+ .ts files and 1,100+ .tsx files, organized as a Yarn 4 + Turborepo monorepo.
• Framework: Next.js 13+ App Router for apps/web. NestJS for apps/api/v2. MintLify for apps/docs.
• Database: PostgreSQL via Prisma ORM. The schema (packages/prisma/schema.prisma) defines 100 models and 46 enums.
• API layer: tRPC for type-safe internal calls (packages/trpc/server/routers), plus REST/OpenAPI for apps/api/v2.
• Auth: NextAuth.js with email/password, magic links, Google, GitHub, SAML (removed in Cal.diy), and a custom Prisma adapter (packages/features/auth/lib/next-auth-custom-adapter.ts).
• UI: Tailwind CSS, shared components in packages/ui, internal feature components scattered through packages/features/*.
• Testing: Vitest for unit tests, Playwright for E2E, Jest for apps/api/v2.
• Tooling: Biome for formatting and linting, Turbo for task orchestration, Husky + lint-staged for git hooks, Sentry for error tracking, Trigger.dev for background jobs.

Quick links

• Architecture — system diagram and how the pieces fit together
• Getting started — prerequisites, install, build, test
• Glossary — project-specific vocabulary
• Apps — web, api/v2, docs
• Packages — workspaces under packages/
• Features — cross-cutting capabilities
• Primitives — domain models that appear across systems
• How to contribute

Audience for this wiki

This wiki is written for engineers landing in the codebase for the first time — what each subsystem does, where it lives, and where to start when you need to change it. It is not a user-facing manual. For end-user docs, see the MintLify content under apps/docs/content/.