utoo-lint

Native at the core

Built in Zig, with Yuku parsing and semantic analysis. Lint files in parallel using prebuilt binaries for macOS, Linux, and Windows.

Made for real projects

JavaScript, TypeScript, React, accessibility, and import rules. Use familiar rule IDs and severities, with safe autofix where supported.

Ready for your workflow

Typed or JSON configuration, suppression comments, and JSON diagnostics. Use the CLI, JavaScript API, or in-memory WebAssembly package.

index.tsTypeScript

Autofix example

typescript

function greet(name: string) {
  let message = `Hello, ${name}`;;
  const messages = new Array(message, 'Welcome');
  return { messages: messages };
}

4 diagnostics with safe autofixes

PERFORMANCE

More feedback. Less waiting.

The same TypeScript corpus. The same 12 shared rules. Every sample starts a fresh CLI process, including startup time.

9.52msutoo-lint median

78.0×faster than ESLint in this run

Read the recorded results

100 TypeScript files · 12 shared rules

Every millisecond counts.

Shorter is faster

Median CLI timems

Select a tool to explore its runsLinear scale from zero

utoo-lintFastest20 measured runs

Observed range9.21–11.04ms

Recorded Aug 30, 2026 · macOS arm64 · Node.js 20.19.1 · 5 warmups per tool.Save chart

A recorded run on one generated workload. Results vary with hardware, code, and enabled rules. The archived report documents the environment and comparison limits.

Reproduce the benchmark ↗Download raw results ↓

CONFIGURATION

Your rules. In your language.

Start with the frontend preset, then adapt it to your project. Typed configuration brings editor completion; static JSON works when you need a data-only config.

ESLint-style rule names and severities
File patterns, global ignores, and flat config arrays
Presets you can extend and override

Explore configuration

utlint.config.tsTypeScript

typescript

import { defineConfig } from '@utoo/lint/config';
import frontend from '@utoo/lint/configs/frontend';

export default defineConfig({
  ...frontend,
  rules: {
    ...frontend.rules,
    'no-console': 'warn',
  },
});

ADOPTION

Start small. Migrate with confidence.

Bring over supported rules at your own pace. The migration report shows what can move and what still needs ESLint.

Inspect your config
Preview the migration before writing files. Review the report for unsupported options and plugin behavior.
utoo-lint migrate eslint --print
Move supported rules
Check coverage for the rules your project uses. Keep unsupported processors, custom plugins, and type-service workflows in ESLint.
Check rule coverage →
Verify in your project
Run both tools in CI and compare diagnostics. Remove duplicate ESLint coverage as each rule is verified.
Read the migration guide →

ONE ENGINE, MULTIPLE RUNTIMES

From your repository to the browser.

Native CLI

Lint your source tree and apply supported fixes, locally or in CI.

pnpm exec utoo-lint srcUse the CLI →

JavaScript API

Integrate linting into Node.js tools with ESM and CommonJS entry points.

@utoo/lintConfigure your project →

WebAssembly

Lint and fix one in-memory file. The Playground processes code locally in your browser.

@utoo/lint-wasmExplore WebAssembly →

Fast linting. Familiar rules.