Onlook is a browser-based visual editor for building and modifying Next.js + Tailwind CSS websites. It provides a Figma-like canvas where users can directly manipulate React components, with changes written back to source code via AST-based transformation. The application integrates an AI chat assistant that can generate code, edit files, and run terminal commands through a set of well-defined tools (e.g., search-replace, file edit, bash). The monorepo architecture separates concerns into packages for AI agents, code parsing, font management, UI components, database access (Drizzle + Supabase), git operations, and sandbox management (CodeSandbox). It also includes a complete billing system (Stripe), GitHub integration for project import, custom domain management, and a publish/deployment pipeline. The codebase demonstrates strong engineering practices with type-safe tRPC APIs, MobX state management in the editor, extensive use of Radix UI primitives, and a consistent monorepo toolchain (Bun workspaces, ESLint, Prettier). While the editor engine is somewhat monolithic, individual packages like the AST parser, font helpers, and utility library are well-isolated and testable.