Coolify is a self-hosted Platform-as-a-Service (PaaS) that enables users to deploy and manage applications, databases, and services on their own infrastructure. It serves as an open-source alternative to Heroku, Netlify, or Vercel, supporting Docker-based deployments with Git integration (GitHub, GitLab, Gitea, Bitbucket), multiple build packs (Railpack, Nixpacks), and one-click service templates. The system manages servers, reverse proxies (Traefik/Caddy), SSL certificates, scheduled backups, and multi-channel notifications (email, Discord, Slack, Telegram, Pushover, webhook). The architecture is a Laravel monolith with a Livewire + Alpine.js frontend for the v4 UI and a React + TypeScript canvas-based interface for the v5 UI. Background jobs are handled by Laravel Horizon with dedicated queues for deployments, cron tasks, and reconciliation. Real-time updates use Soketi (a Pusher-compatible WebSocket server) and Laravel Echo. The system integrates with cloud providers (Hetzner, Vultr, DigitalOcean) for server provisioning and Stripe for subscription billing. A Model Context Protocol (MCP) server exposes resources and tools for AI assistant integration. Key data flows include: webhook ingestion from Git providers triggering deployment jobs, SSH-based remote command execution on managed servers, Docker Compose parsing and environment variable injection, database backup scheduling with S3 storage, and proxy configuration generation. The v5 architecture introduces a control-plane/agent split with Flux (HTTP socket) and coold (gRPC) components for improved scalability and isolation. External dependencies include Docker, PostgreSQL, Redis, Soketi, Stripe API, cloud provider APIs, and various notification service endpoints. The codebase is actively developed with frequent schema migrations and a dual v4/v5 code path, indicating ongoing architectural evolution.