Foldkit

Foldkit is a TypeScript frontend framework built on Effect-TS that follows The Elm Architecture. It addresses the architectural decisions left to developers by rendering-focused libraries such as React, Vue, Svelte, and Solid by supplying a structured approach centered on predictable state management and explicit effects.

The framework maintains one immutable model for the entire application state. Every change passes through a single pure update function, eliminating hidden mutations and stale closures. Side effects appear as values returned from the update function rather than imperative calls inside event handlers. These commands describe intended actions while the runtime determines execution details. The design produces linear growth in complexity, allowing a 50-file application to retain the same patterns as a 5-file one. New team members can read the codebase and understand its structure more readily. Every Foldkit application is an Effect, with state represented as a single Schema and side effects modeled as Effects that never fail.

It integrates Effect throughout its implementation. Developers familiar with Effect find the framework natural to use, while newcomers can treat it as an introduction to the library. A live playground demonstrates message flow through the update function into the model, with real-time code highlighting. Installation uses the command npx create-foldkit-app@latest. The project maintains a public repository on GitHub.

Foldkit remains in beta. It serves teams that prioritize correctness and explicitness over other frontend approaches.