Biome Config Builder

Biome Config Builder

Compose biome.json for the Biome formatter and linter with per-rule severity and one-binary tooling.

Formatter

JavaScript / TypeScript

Linter

correctness
security
suspicious
style
complexity
performance
a11y

Files & VCS

biome.json
{
  "$schema": "https://biomejs.dev/schemas/2.0.0/schema.json",
  "vcs": {
    "enabled": true,
    "clientKind": "git",
    "useIgnoreFile": true
  },
  "files": {
    "ignore": [
      "node_modules",
      "dist",
      "build",
      "coverage"
    ]
  },
  "organizeImports": {
    "enabled": true
  },
  "formatter": {
    "enabled": true,
    "indentStyle": "space",
    "indentWidth": 2,
    "lineWidth": 80,
    "lineEnding": "lf"
  },
  "linter": {
    "enabled": true,
    "rules": {
      "recommended": true,
      "correctness": {
        "recommended": true,
        "noUnusedVariables": "error"
      },
      "security": {
        "recommended": true,
        "noDangerouslySetInnerHtml": "error"
      },
      "style": {
        "recommended": true,
        "useConst": "warn"
      },
      "suspicious": {
        "recommended": true,
        "noDebugger": "warn"
      },
      "complexity": {
        "recommended": true,
        "noUselessFragments": "warn"
      },
      "performance": {
        "recommended": true,
        "noAccumulatingSpread": "warn"
      },
      "a11y": {
        "recommended": true,
        "useAltText": "warn"
      }
    }
  },
  "javascript": {
    "formatter": {
      "quoteStyle": "double",
      "jsxQuoteStyle": "double",
      "trailingCommas": "all",
      "semicolons": "always",
      "arrowParentheses": "always"
    }
  },
  "json": {
    "formatter": {
      "trailingCommas": "none"
    }
  }
}

What This Tool Does

Biome Config Builder is built for deterministic developer and agent workflows.

Compose biome.json for the Biome formatter and linter with formatter, linter, organize-imports, and per-rule severity. Side-by-side comparison against an equivalent ESLint+Prettier setup.

Use How to Use for execution steps and FAQ for constraints, policies, and edge cases.

Last updated:

This tool is provided as-is for convenience. Output should be verified before use in any production or critical context.

Agent Invocation

Best Path For Builders

Browser workflow

Runs instantly in the browser with private local processing and copy/export-ready output.

Browser Workflow

This tool is optimized for instant in-browser execution with local data handling. Run it here and copy/export the output directly.

/biome-config-builder/

For automation planning, fetch the canonical contract at /api/tool/biome-config-builder.json.

How to Use Biome Config Builder

  1. 1

    Configure the formatter

    Set indentStyle, indentWidth, lineWidth, and lineEnding. The JS/TS panel adds quoteStyle, trailingCommas, semicolons, and arrowParentheses for full Prettier-compatible output.

  2. 2

    Tune the linter groups

    Pick a severity per rule group: correctness, security, suspicious, style, complexity, performance, and a11y. Each maps to Biome's recommended rules with your chosen severity.

  3. 3

    Toggle organize-imports and VCS

    Enable Organize imports on save and VCS integration to honor your .gitignore. Add file-level ignores like dist or coverage so Biome skips them entirely.

  4. 4

    Compare with ESLint+Prettier

    Click Show ESLint+Prettier compare to see the equivalent dual-tool setup and a side-by-side feature table covering install size, speed, and rule coverage.

  5. 5

    Copy biome.json

    Review the generated biome.json and click Copy. Save it to your repo root and run bunx biome check . or biome format . to apply the configuration.

Frequently Asked Questions

What is Biome Config Builder?
A visual composer for biome.json, the single config file used by Biome (the Rust-based formatter and linter). It covers formatter options, linter rule groups, organize-imports, and VCS integration.
How does Biome compare to ESLint+Prettier?
Biome is a single binary that formats and lints in one pass, written in Rust. The compare panel shows install size, speed, and feature parity differences across both setups.
Can I customize per-rule severity?
Yes. The linter section exposes the seven Biome rule groups (correctness, security, suspicious, style, complexity, performance, a11y) with off, info, warn, and error severities.
Does it send my data to a server?
No. The builder is fully client-side. Settings render to JSON in your browser and never get transmitted anywhere.
Where do I put biome.json?
At your project root next to package.json. Run biome check ., biome format ., or set up an editor extension that reads the file automatically on save.