Coi
lastmod 2026-02-07created 2026-02-071 edits
Coi: A type-safe, component-based language for building high-performance web apps with WASM and fine-grained reactivity.
A component-based language for building reactive web apps
About
- A component-based language designed for developing high-performance web applications
- Combines WASM (WebAssembly) with a fine-grained reactivity architecture
- Centered on type safety, it catches errors at compile time to ensure stable code quality
- Memory management without a garbage collector (GC) provides predictable performance and an execution environment without frame delays
- With a fine-grained reactive system, state changes map directly to DOM elements, eliminating Virtual DOM overhead
- Batch operations group browser API calls such as DOM, Canvas, and Storage to minimize WASM–JS boundary costs
- Component-based design supports props, state, and lifecycle blocks, and provides declarative control-flow tags such as <if> and <for>
- Syntax that lets you write HTML and CSS together, with scope-based styling support
- Editor extensions provided for VS Code, Sublime Text, and Zed
- Create and run projects with CLI commands such as coi init, coi build, and coi dev