Fre is a lightweight concurrent UI library with Fiber architecture that brings React-like development patterns to a minimal codebase.
The library addresses the need for a small-footprint UI framework that does not sacrifice modern features. It implements concurrent mode through a coroutine scheduler that enables time slicing, allowing the browser to interrupt rendering work and handle high-priority tasks. The core reconciliation algorithm is keyed and minimal, supporting pre-process rendering, offscreen rendering, and server-side hydration. The tool provides virtual DOM, hooks API, Suspense, Fragments, and memoization despite its tiny size.
Fre suits developers building projects where bundle size matters but who want familiar React-like APIs and patterns. The hooks API covers useState, useEffect, useReducer, useLayout, useCallback, useMemo, useRef, and useContext. The library includes ErrorBoundary for error handling and memo for component optimization. Teams evaluating adoption should note that the concurrent mode implementation via time slicing is a distinguishing feature that allows rendering work to be split across multiple frames, preventing long tasks from blocking user interaction.
The project maintains active test coverage and builds successfully through continuous integration. Development activity shows ongoing maintenance with regular updates to the codebase and attention to code quality metrics.
