# kaleidawave/ezno

A correct and efficient TypeScript type checker and compiler with additional experiments

Repository: https://github.com/kaleidawave/ezno
Canonical: https://ross.abutalabs.com/products/ezno
Homepage: https://kaleidawave.github.io/posts/introducing-ezno/
Language: Rust
License: MIT
License Family: permissive
Topics: compiler, javascript, typescript, typechecker
Last push: 2026-06-16T19:49:29+00:00

## Health v2 (maintenance only)
Score: 61/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 87, release rhythm 8, longevity 93
- inputs: {"age_days": 1307, "days_push": 78, "days_rel": 658, "gap_med": null, "n_releases_24m": 1}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2735, forks 49 (observed 2026-08-28T04:07:16.296159+00:00)

## What it is
Ezno is an experimental TypeScript/JavaScript type checker and compiler written in Rust, usable as a CLI or library. It features a sound imperative type system that tracks side effects and evaluates control flow with types rather than values, aiming to guarantee no runtime TypeErrors.

## Use cases
- type check a JavaScript or TypeScript project from the command line
- catch runtime TypeErrors statically before they happen
- experiment with an imperative type system that tracks function side effects
- use a fast Rust-based alternative to TSC for checking code
- explore dependent typing and constant evaluation in JavaScript
- integrate a type checker as a Rust library into other tooling

## When to choose
- you want to experiment with a novel, soundness-focused type checker for JavaScript
- you need a fast, small type-checking CLI written in Rust
- you are researching side-effect tracking and dependent types in dynamic languages
- you want to contribute to an open-source compiler project with good first issues

## When to avoid
- you need full TypeScript feature parity for checking an existing production codebase
- you need a mature, stable checker for large codebases today
- you need a compiler that emits lower-level output rather than JavaScript
- you require an LSP or editor integration right now

## Facets
- artifact type: cli-tool
- maturity: experimental
- function: compiler, type-system, linter, parser, cli
- domain: programming-languages, compilers, developer-tools, web-development
- platform: cli, rust, cross-platform
- tags: typescript, javascript, type-checker, static-analysis, soundness, dependent-types, side-effect-analysis

## Member repositories
- kaleidawave/ezno (main) score 61

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:07:16.296159+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T02:14:27.466415+00:00, confidence not recorded.
  - readme: https://github.com/kaleidawave/ezno (fetched 2026-08-28T04:07:16.296159+00:00, sha 8c78242f4742)
  - homepage: https://kaleidawave.github.io/posts/introducing-ezno/ (fetched 2026-08-29T09:57:31.951362+00:00, sha 7341a60fcf8f)
  - site_page: https://kaleidawave.blog/about (fetched 2026-08-29T09:57:31.961288+00:00, sha d9ea8ef82c69)
  - registry_crates: https://crates.io/api/v1/crates/ezno (fetched 2026-08-29T09:57:31.962930+00:00, sha 3bae797c232b)
- Data as of 2026-08-30T08:39:29.467469+00:00.