HeyForm is an open-source form builder and management platform designed for small businesses. It provides a full-stack solution with a React-based drag-and-drop form builder, a NestJS GraphQL API backend, a standalone form renderer for public-facing forms, and an embed script for third-party sites. The system supports a wide range of field types (text, choice, rating, payment, signature, etc.), conditional logic with branching, multi-language internationalization, Stripe payments, AI-assisted form generation via OpenAI, and integrations with popular services like Slack, Notion, and Google Sheets. The architecture follows a monorepo pattern with shared packages for answer validation, utility functions, and type definitions, enabling code reuse across the server, webapp, and renderer. The backend is built with NestJS, MongoDB (Mongoose), Redis (Bull queues), and Apollo GraphQL, with scheduled jobs for cleanup and async task processing. The frontend uses React 19, Tailwind CSS, Zustand for state management, and Apollo Client for GraphQL communication. Security is a strong focus: the codebase includes SSRF protection, upload content validation, rate limiting, atomic verification codes, and extensive input sanitization. The project has a comprehensive test suite covering unit, integration, and end-to-end scenarios, including a permission matrix with over 270 cases. Despite some duplicated logic and large locale files, the overall code quality is high, with well-structured modules and clear separation of concerns.