Biome Configurations

Shared Biome configuration presets — a base recommended config plus a family of React presets (recommended, strict, balanced, and nursery-free -stable variants) that you extend in your own biome.json.

• One line to adopt — extends a preset and inherit the formatter, linter, and assist settings together.
• A ladder, not a single opinion — six presets, from Biome's own recommended baseline up to 254 explicitly configured rules.
• React, Next.js, and React Native — framework rules are enabled by name, so they apply without relying on domain auto-detection.
• Nursery-free -stable variants — the same rule sets minus Biome's experimental rules, for teams that want a surface that will not shift under them.
• Plain JSON, no runtime dependencies — the presets are published as config files; Biome is the only thing installed alongside them.
• Dogfooded — this repository formats and lints itself with the base preset.

Table of Contents

• Requirements
• Installation
• Configurations
• Usage
• Defaults
• Rules
• FAQ
• Versioning
• Contributing
• License

Requirements

| Dependency | Version | |---|---| | Biome | 2.5.5+ — the release the presets target | | Node.js | >= 24 — declared in the package's engines |

Biome is not bundled, so install a compatible version yourself. The presets pin their $schema to https://biomejs.dev/schemas/2.5.5/schema.json; using that same URL in your own biome.json matches the presets exactly and silences editor warnings about unknown fields.

Installation

Install the presets together with Biome as dev dependencies:

# npm
npm install -D @dvashim/biome-config @biomejs/biome

# pnpm
pnpm add -D @dvashim/biome-config @biomejs/biome

# yarn
yarn add -D @dvashim/biome-config @biomejs/biome

# bun
bun add -d @dvashim/biome-config @biomejs/biome

Configurations

| Preset | extends path | Explicit rules | Nursery | |--------|----------------|----------------|---------| | Base recommended | @dvashim/biome-config | Biome recommended only | — | | React recommended | @dvashim/biome-config/react-recommended | Biome recommended + React domain | — | | React strict | @dvashim/biome-config/react-strict | 254 | 72 | | React strict-stable | @dvashim/biome-config/react-strict-stable | 182 | — | | React balanced | @dvashim/biome-config/react-balanced | 254, 15 relaxed | 72 | | React balanced-stable | @dvashim/biome-config/react-balanced-stable | 182, 15 relaxed | — |

"Explicit rules" counts the entries a preset configures itself; Biome's recommended rules stay active in every preset on top of them. All six share the same formatter, parser, VCS, and assist defaults.

Each preset has a second export path with a slash — @dvashim/biome-config/react/balanced is the same file as @dvashim/biome-config/react-balanced — and the base config is also exported as @dvashim/biome-config/recommended.

Not sure which to pick? See Which config should I start with? in the FAQ.

Usage

Add a biome.json to your project root and extend a preset. The extends path is the only line that changes between presets:

// biome.json
{
  "$schema": "https://biomejs.dev/schemas/2.5.5/schema.json",
  "extends": ["@dvashim/biome-config"]
}

Then run Biome:

pnpm exec biome check          # report formatting, lint, and assist issues
pnpm exec biome check --write  # apply the safe fixes

Or wire it into your package.json:

{
  "scripts": {
    "check": "biome check",
    "fix": "biome check --write",
    "format": "biome format --write"
  }
}

For format-on-save and inline diagnostics, install Biome's first-party editor extension.

Note: The React presets automatically exclude build output (files.includes: ["**", "!!**/dist"]); the base preset sets no files.includes, so Biome processes all supported files by default.

Defaults

All six configurations share the same base defaults — they differ only in files.includes and linter rules.

Formatter

| Option | Value | |--------|-------| | attributePosition | "auto" | | bracketSameLine | false | | bracketSpacing | true | | expand | "auto" | | formatWithErrors | false | | indentStyle | "space" | | indentWidth | 2 | | lineEnding | "lf" | | lineWidth | 80 | | useEditorconfig | true |

JavaScript formatter

| Option | Value | |--------|-------| | arrowParentheses | "always" | | jsxQuoteStyle | "double" | | operatorLinebreak | "before" | | quoteProperties | "asNeeded" | | quoteStyle | "single" | | semicolons | "asNeeded" | | trailingCommas | "es5" |

JavaScript

| Option | Value | |--------|-------| | experimentalEmbeddedSnippetsEnabled | true | | globals | [] | | jsxRuntime | "transparent" | | parser.gritMetavariables | false | | parser.jsxEverywhere | true | | parser.unsafeParameterDecoratorsEnabled | false |

JSON parser

| Option | Value | |--------|-------| | allowComments | true | | allowTrailingCommas | true |

HTML

| Option | Value | |--------|-------| | experimentalFullSupportEnabled | true |

Files (React presets only)

| Option | Value | |--------|-------| | includes | ["**", "!!**/dist"] |

VCS

| Option | Value | |--------|-------| | clientKind | "git" | | enabled | true | | defaultBranch | "main" | | useIgnoreFile | true |

Assist

| Option | Value | |--------|-------| | actions.recommended | true | | actions.source.noDuplicateClasses | "on" |

Overrides

| File pattern | Setting | Value | |------|---------|-------| | **/package.json | assist.actions.source.useSortedKeys | "off" | | **/package.json | json.formatter.expand | "always" |

Rules

Base recommended

Enables all recommended Biome rules out of the box with no custom overrides. Provides sensible defaults for code quality, correctness, and best practices across JavaScript, JSX, JSON, and HTML.

React recommended

Same as base recommended, plus enables the React domain ("react": "recommended"), which activates React-specific recommended rules for hooks, JSX, and component patterns.

React strict

The most opinionated configuration. Enables all recommended rules plus 254 optional and nursery rules across 8 categories. Every non-recommended rule that applies to JavaScript/TypeScript/JSX, CSS, HTML, JSON, or the React, Next.js, and React Native domains is explicitly configured. Rules exclusive to GraphQL or other frameworks (Vue, Solid, Qwik, Svelte) are intentionally omitted.

• a11y (8 rules) — Selectively disables noisy rules (useButtonType, useKeyWithClickEvents, useSemanticElements, noStaticElementInteractions, noNoninteractiveElementToInteractiveRole) and downgrades useFocusableInteractive to info, while keeping the rest at recommended defaults. Adds noAmbiguousAnchorText (promoted from nursery in Biome 2.5.0) and noNoninteractiveElementInteractions.

• complexity (16 rules) — Monitors cognitive complexity, function length, nested test suites, and logic expressions. Warns on forEach, implicit coercions, void, and useless patterns. Also prefers Array#find (useArrayFind) and flags useless returns (noUselessReturn), redundant default exports (noRedundantDefaultExport), and division-like regexes (noDivRegex).

• correctness (25 rules) — Ensures no undeclared variables/dependencies, proper React patterns (noReactPropAssignments, noNestedComponentDefinitions, noChildrenProp, noRenderReturnValue), React Hooks correctness (useExhaustiveDependencies, useHookAtTopLevel, useJsxKeyInIterable), Node.js guards (noNodejsModules, noProcessGlobal, noGlobalDirnameFilename), and JSON import attributes. noUnresolvedImports is disabled since TypeScript already performs these checks. Also flags duplicate JSX attributes (noDuplicateAttributes), duplicate enum member names (noDuplicateEnumValueNames), unused new expressions (noUnusedInstantiation), restricted imports/elements (noPrivateImports, noRestrictedElements), and Next.js issues (noNextAsyncClientComponent, useInlineScriptId, noBeforeInteractiveScriptOutsideDocument).

• nursery (72 rules) — Opts into all experimental rules. Highlights include:

  • Errors: noMisusedPromises
  • Equality: noNegationInEqualityCheck (flags !foo === bar, which precedence parses as (!foo) === bar — almost always meant as foo !== bar)
  • Complexity: noExcessiveNestedCallbacks
  • Promises: noFloatingPromises, useAwaitThenable
  • TypeScript: useExhaustiveSwitchCases, useExplicitReturnType, noMisleadingReturnType, noUselessTypeConversion, useNullishCoalescing, useReduceTypeParameter
  • Object/class hygiene: noBaseToString (catches accidental "[object Object]" stringification), useThisInClassMethods
  • Resource management: useDisposables (enforces using for Disposable/AsyncDisposable)
  • Arrays: useArraySome, useIncludes (prefer Array#includes() over indexOf() — new in Biome 2.5.0)
  • Regex: useNamedCaptureGroup, useUnicodeRegex, useRegexpExec, useRegexpTest
  • DOM: useDomNodeTextContent, useDomQuerySelector
  • Math: useMathMinMax
  • Styling: noDuplicateSelectors, noInlineStyles, noExcessiveSelectorClasses, noUndeclaredClasses, noUnusedClasses
  • Testing: useConsistentTestIt, useExpect, noConditionalExpect, noIdenticalTestTitle, useTestHooksInOrder, useTestHooksOnTop
  • Playwright: Full suite of 11 Playwright rules
  • Drizzle: noDrizzleDeleteWithoutWhere, noDrizzleUpdateWithoutWhere
  • Tailwind: useSortedClasses
  • React: useReactAsyncServerFunction, noComponentHookFactories, noJsxNamespace, noReactStringRefs, useReactFunctionComponentDefinition
  • React Native: noReactNativeRawText, noReactNativeLiteralColors, noReactNativeDeepImports, useReactNativePlatformComponents
  • Security: useIframeSandbox
  • Dependencies: noUntrustedLicenses, noRestrictedDependencies
  • Disabled: useExplicitType

  Biome 2.5.0 graduated many rules out of nursery; the rules that previously lived here are now configured under their stable categories above (and consequently appear in the -stable variants).

• performance (11 rules) — Warns on await in loops, barrel files, delete, namespace imports, re-export all, non-top-level regex, synchronous scripts (noSyncScripts), and binding props in JSX (noJsxPropsBind, error). Adds Next.js performance rules (noImgElement, noUnwantedPolyfillio, useGoogleFontPreconnect).

• security (4 rules) — noSecrets, noScriptUrl, and React dangerouslySetInnerHTML guards (noDangerouslySetInnerHtml, noDangerouslySetInnerHtmlWithChildren)

• style (76 rules) — Enforces consistent syntax, naming conventions (strictCase: true), array shorthand syntax, type over interface, React function components, readonly class properties, noDefaultExport, noMagicNumbers, noJsxLiterals, and more. Now also includes rules promoted from nursery in Biome 2.5.0, such as noIncrementDecrement, noMultiAssign, noMultilineString, noTernary, useDestructuring, useErrorCause, useGlobalThis, and useSpreadOverApply. Adds noHexColors, noValueAtRule, useNodeAssertStrict, the configurable noRestrictedGlobals / noRestrictedImports / noRestrictedTypes family, and the Next.js noHeadElement rule.

• suspicious (42 rules) — Flags var (error), console, alert, bitwise operators, empty blocks, import cycles, evolving types, skipped tests, and deprecated imports. Now also includes rules promoted from nursery in Biome 2.5.0, such as noShadow, noUnnecessaryConditions, noForIn, noEqualsToNull, noLeakedRender, and noParametersOnlyUsedInRecursion. Adds noArrayIndexKey, test-quality rules (noFocusedTests, noDuplicateTestHooks, noExportsInTest), useDeprecatedDate, useRequiredScripts, and Next.js document rules (noDocumentImportInPage, noHeadImportInDocument).

React strict-stable

Same as React strict, but without nursery (experimental) rules — 182 rules across 7 categories: a11y, complexity, correctness, performance, security, style, and suspicious.

React balanced

Same rule set as strict, with 15 targeted relaxations to reduce false positives and noise in real-world projects:

| Category | Rule | Strict | Balanced | Reason | |----------|------|--------|----------|--------| | complexity | noExcessiveLinesPerFunction | warn (default) | warn (maxLines: 100) | Higher threshold | | complexity | noImplicitCoercions | warn | off | Too noisy with !!value patterns | | complexity | noUselessReturn | warn | info | Informational only | | performance | noBarrelFile | warn | off | Common pattern in libraries | | performance | noImgElement | warn | off | Next.js rule; fires on any <img> | | performance | noNamespaceImport | warn | off | Allows import * as | | performance | noReExportAll | warn | off | Common pattern in libraries | | style | noContinue | warn | info | Informational only | | style | noDefaultExport | warn | off | Allows default exports | | style | noImplicitBoolean | warn | info | Informational only | | style | noIncrementDecrement | warn | warn (allowForLoopAfterthoughts) | Allows i++ in for loops | | style | noJsxLiterals | warn | off | Allows inline text in JSX | | style | noMagicNumbers | warn | info | Informational only | | style | noNestedTernary | warn | off | Allows nested ternaries | | style | useNamingConvention | strictCase: true | strictCase: false | More lenient casing |

Every relaxation lives in a stable category, so all 15 apply in react-balanced-stable as well.

React balanced-stable

Same as React balanced, but without nursery (experimental) rules — 182 rules, with all relaxations from the table above still applied.

FAQ

Which config should I start with?

• Non-React projects — use @dvashim/biome-config (base recommended).
• React projects — start with react-balanced for a good trade-off between strictness and practicality. Move to react-strict once your codebase is clean, or react-recommended if you only want Biome's built-in defaults. Use the -stable variants if you want to avoid nursery (experimental) rules.

What version of Biome and Node do I need?

These presets are built and tested against Biome 2.5.5 — the version their $schema is pinned to (see Requirements) — and require Node.js >= 24. Biome is not bundled, so install a compatible version yourself:

pnpm add -D @biomejs/biome@^2.5.5

How do I override a rule from the preset?

Add a linter.rules section in your biome.json. Local settings merge with and take precedence over the preset:

{
  "$schema": "https://biomejs.dev/schemas/latest/schema.json",
  "extends": ["@dvashim/biome-config/react-balanced"],
  "linter": {
    "rules": {
      "style": {
        "noDefaultExport": "error"
      }
    }
  }
}

The Rules section lists each rule under its category, which is the key you need for the override.

Why do I see Next.js diagnostics in a project that is not Next.js?

react-strict and react-balanced set no domains key — every framework rule is enabled by name instead of by domain detection, so it applies to all your files. A few of them fire on patterns that are fine outside their framework; noImgElement flagging any <img> is the usual one.

react-balanced already turns the broadest ones off. To silence one yourself, override it by category:

{
  "extends": ["@dvashim/biome-config/react-strict"],
  "linter": {
    "rules": {
      "performance": {
        "noImgElement": "off"
      }
    }
  }
}

How do I exclude additional files or directories?

The simplest approach is to add paths to your .gitignore — all presets enable vcs.useIgnoreFile, so Biome respects .gitignore patterns automatically.

For exclusions that should not affect Git tracking, use negated patterns in files.includes. The !! prefix force-ignores paths (prevents scanning entirely), while ! excludes matches from results:

{
  "$schema": "https://biomejs.dev/schemas/latest/schema.json",
  "extends": ["@dvashim/biome-config"],
  "files": {
    "includes": ["**", "!!**/generated", "!!**/coverage"]
  }
}

Why does the base config not set files.includes?

The base recommended config intentionally omits files.includes so consumers control their own file scope. Biome processes all supported files by default when no includes is set. The React configs set files.includes to ["**", "!!**/dist"] to explicitly exclude build output.

Can I use this with TypeScript?

Yes. Biome natively supports TypeScript — no additional configuration is needed. All presets apply to .ts and .tsx files automatically.

Can I use this in a monorepo?

Yes. Install the package at the root and reference it in each workspace's biome.json. Each workspace can extend a different preset and add its own overrides.

How do I migrate from ESLint and Prettier?

Extend a preset first, then let Biome import whatever your existing setup configured on top of it:

pnpm exec biome migrate eslint --write
pnpm exec biome migrate prettier --write

See Biome's migration guide for the details and known gaps.

Versioning

Releases are sized by the effect they have on the diagnostics you receive:

• minor — a preset's rule list changed: a rule was added, removed, renamed, or re-leveled. Expect new or different diagnostics.
• patch — the presets moved to a newer Biome release with no rule-list change, or documentation was corrected.

Because a minor release can surface new warnings, pin the version if your CI treats lint output as a hard failure. The CHANGELOG records the rules each release touched.

Contributing

Issues and pull requests are welcome. The repo uses pnpm and Changesets:

1. pnpm install
2. Edit the presets in dist/ — they are checked in directly, so there is no build step. After changing react-strict or react-balanced, run pnpm run sync-stable to regenerate the -stable variants.
3. biome check --write to apply formatting and the sorted-key assist.
4. pnpm run check to validate formatting, package exports, -stable sync, and types.
5. pnpm changeset to record a user-facing change.

To report a security issue, see SECURITY.md.

License

MIT