This is a monorepo for SurveyJS, a comprehensive open-source form/survey library that renders dynamic JSON-based forms across multiple frontend frameworks (React, Angular, Vue 3, and plain JavaScript). The core engine (`survey-core`) handles model parsing, validation, expressions, triggers, input masks, drag-and-drop, theming, and localization. It provides 20+ question types (text, checkbox, radio, dropdown, matrix, ranking, file, signature, etc.) with extensible UI components via framework-specific rendering packages. The library also includes a built-in linter for survey JSON static analysis and a tester for programmatic survey test execution. Architecture follows a layered pattern: core logic separate from UI, with each framework package consuming the core via a shared set of exported model classes. The codebase is large (2896 files) but well-structured, featuring a custom expression parser (PEG), a modular action-bar system, advanced popup management with focus trapping, and a generic drag-drop engine. Maintenance is active with frequent releases, but there is some technical drift in the form of commented-out legacy testcafe tests, auto-generated theme files, and cross-framework duplication that requires careful synchronization.