Umami is a self-hosted, open-source web analytics platform that serves as a privacy-focused alternative to Google Analytics. The system tracks pageviews, sessions, events, funnels, journeys, retention, attribution, revenue, and performance metrics (Core Web Vitals) through a dual-database architecture using PostgreSQL (via Prisma ORM) and ClickHouse for analytics queries. It provides real-time dashboards, session replay, heatmaps, and a customizable board/dashboard system with shareable views. The application is built with Next.js (App Router) and React, using TypeScript throughout. It features a comprehensive REST API with auto-generated OpenAPI contracts, a generated TypeScript API client package, and an MCP (Model Context Protocol) server for AI/LLM integration. Authentication supports API keys, JWT, two-factor authentication (TOTP with backup codes), and team-based multi-tenancy with role-based permissions. Key architectural patterns include a dual-database query dispatcher (`runQuery`) that selects between Prisma and ClickHouse implementations for every analytics query, a centralized request parsing and validation layer using Zod schemas, and a hook-based React data layer with TanStack Query for caching and invalidation. The codebase also includes comprehensive test coverage with Vitest unit tests, Playwright API tests, and E2E tests, plus a coverage oracle that enforces every API endpoint is documented in the OpenAPI spec.