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Oxlint is part of the Oxc project, a collection of high-performance JavaScript tools written in Rust. Paired with Oxfmt for formatting, this toolchain is ideal for large codebases where speed is critical.

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Benefits

  • 50-100x faster — Lint your entire codebase in milliseconds
  • 15 plugin equivalents — Built-in support for React, TypeScript, Next.js, Vue, Jest, Vitest, and more
  • Bug-focused rules — Prioritizes catching real bugs over stylistic issues
  • High signal-to-noise ratio — Fewer false positives, more actionable feedback
  • Oxc ecosystem — Part of a larger project with parser, resolver, transformer, and minifier
  • Drop-in ready — Works alongside existing setups or as a complete replacement

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Usage

Ultracite generates two config files for Oxlint:
.oxlintrc.json
{
  "extends": ["./node_modules/ultracite/config/oxlint/core/.oxlintrc.json"]
}
.oxfmtrc.jsonc
{
  "tabWidth": 2,
  "useTabs": false,
  "semi": true,
  "singleQuote": false,
  "trailingComma": "es5",
  "bracketSpacing": true,
  "arrowParens": "always",
  "printWidth": 80
}
Add framework presets as needed:
.oxlintrc.json
{
  "extends": [
    "./node_modules/ultracite/config/oxlint/core/.oxlintrc.json",
    "./node_modules/ultracite/config/oxlint/react/.oxlintrc.json",
    "./node_modules/ultracite/config/oxlint/next/.oxlintrc.json"
  ]
}

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Configuration Approach

Ultracite’s Oxlint configuration uses an opt-out approach. This means we enable all rule categories at the error level, then selectively disable rules that are too strict or don’t fit our opinionated defaults. This ensures maximum bug-catching coverage while avoiding noise.

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Rule Categories

Oxlint organizes rules into the following categories:

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Correctness

Rules that catch definite bugs and errors. These are high-confidence rules that identify code that is almost certainly wrong.

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Suspicious

Rules that catch code patterns that are likely bugs or mistakes. These have a slightly higher false-positive rate but catch important issues.

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Pedantic

Rules that enforce stricter coding standards. These are more opinionated and may require more effort to satisfy.

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Performance

Rules that identify performance issues and suggest optimizations for better runtime efficiency.

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Restriction

Rules that restrict certain language features or patterns. These are typically project-specific preferences.

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Style

Rules that enforce consistent code style across the codebase.

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Included Plugins

Oxlint includes built-in support equivalent to these ESLint plugins:
  • eslint — Core JavaScript rules
  • typescript — TypeScript-specific rules
  • unicorn — Opinionated code quality rules
  • oxc — Oxc-specific optimizations
  • import — Import/export validation
  • jsdoc — JSDoc comment validation
  • node — Node.js-specific rules
  • promise — Promise and async/await best practices
  • jest / vitest — Testing framework rules

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Formatter Settings (Oxfmt)

Ultracite configures Oxfmt with these defaults:
  • Indentation: 2 spaces
  • Line Width: 80 characters
  • Semicolons: Always required
  • Double Quotes: Yes
  • Trailing Commas: ES5 style
  • Arrow Parentheses: Always include

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Rule Reference

For the complete list of rules and their settings, see the Oxlint configuration on GitHub.

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VS Code Extension

Install the Oxc extension for VS Code:
Terminal
code --install-extension oxc.oxc-vscode