diff --git a/package.json b/package.json
index f2cccf75b8..5946d3289f 100644
--- a/package.json
+++ b/package.json
@@ -37,6 +37,7 @@
 		"watch": "pnpm dev",
 		"dev": "node scripts/dev.mjs",
 		"lint": "pnpm -r lint",
+		"biome-lint": "pnpm -r biome-lint",
 		"cy:open": "pnpm cypress open --browser --e2e --config-file=cypress.config.ts",
 		"cy:run": "pnpm cypress run",
 		"e2e": "pnpm start-server-and-test start:test http://localhost:61812 cy:run",
@@ -68,6 +69,7 @@
 		"glob": "11.0.0"
 	},
 	"devDependencies": {
+		"@biomejs/biome": "1.9.3",
 		"@misskey-dev/eslint-plugin": "2.0.3",
 		"@types/node": "20.14.12",
 		"@typescript-eslint/eslint-plugin": "7.17.0",
diff --git a/packages/backend/biome.json b/packages/backend/biome.json
new file mode 100644
index 0000000000..ab73fd8682
--- /dev/null
+++ b/packages/backend/biome.json
@@ -0,0 +1,127 @@
+{
+	"$schema": "https://biomejs.dev/schemas/1.8.3/schema.json",
+	"organizeImports": { "enabled": true },
+	"linter": {
+		"enabled": true,
+		"rules": {
+			"recommended": false,
+			"complexity": {
+				"noBannedTypes": "error",
+				"noExtraBooleanCast": "error",
+				"noMultipleSpacesInRegularExpressionLiterals": "error",
+				"noUselessCatch": "error",
+				"noUselessTypeConstraint": "error",
+				"noWith": "error"
+			},
+			"correctness": {
+				"noConstAssign": "error",
+				"noConstantCondition": "warn",
+				"noEmptyCharacterClassInRegex": "error",
+				"noEmptyPattern": "warn",
+				"noGlobalObjectCalls": "error",
+				"noInnerDeclarations": "off",
+				"noInvalidConstructorSuper": "error",
+				"noNewSymbol": "error",
+				"noNonoctalDecimalEscape": "error",
+				"noPrecisionLoss": "error",
+				"noSelfAssign": "error",
+				"noSetterReturn": "error",
+				"noSwitchDeclarations": "error",
+				"noUndeclaredVariables": "error",
+				"noUnreachable": "error",
+				"noUnreachableSuper": "error",
+				"noUnsafeFinally": "error",
+				"noUnsafeOptionalChaining": "error",
+				"noUnusedLabels": "error",
+				"noUnusedVariables": "error",
+				"useArrayLiterals": "off",
+				"useIsNan": "error",
+				"useValidForDirection": "error",
+				"useYield": "error"
+			},
+			"style": {
+				"noDefaultExport": "warn",
+				"noInferrableTypes": "warn",
+				"noNamespace": "error",
+				"noNonNullAssertion": "warn",
+				"noParameterAssign": "warn",
+				"noRestrictedGlobals": {
+					"level": "error",
+					"options": { "deniedGlobals": ["__dirname", "__filename"] }
+				},
+				"noVar": "error",
+				"useAsConstAssertion": "error"
+			},
+			"suspicious": {
+				"noAsyncPromiseExecutor": "off",
+				"noCatchAssign": "error",
+				"noClassAssign": "error",
+				"noCompareNegZero": "error",
+				"noControlCharactersInRegex": "warn",
+				"noDebugger": "error",
+				"noDoubleEquals": "error",
+				"noDuplicateCase": "error",
+				"noDuplicateClassMembers": "error",
+				"noDuplicateObjectKeys": "error",
+				"noDuplicateParameters": "error",
+				"noEmptyBlockStatements": "off",
+				"noExplicitAny": "warn",
+				"noExtraNonNullAssertion": "error",
+				"noFallthroughSwitchClause": "error",
+				"noFunctionAssign": "error",
+				"noGlobalAssign": "error",
+				"noImportAssign": "error",
+				"noMisleadingCharacterClass": "error",
+				"noMisleadingInstantiator": "error",
+				"noPrototypeBuiltins": "error",
+				"noRedeclare": "error",
+				"noShadowRestrictedNames": "error",
+				"noUnsafeDeclarationMerging": "error",
+				"noUnsafeNegation": "error",
+				"useGetterReturn": "error",
+				"useValidTypeof": "error"
+			}
+		},
+		"ignore": [
+			"**/node_modules",
+			"built",
+			"@types/**/*",
+			"migration"
+		]
+	},
+	"overrides": [
+		{
+			"include": ["*.ts", "*.tsx", "*.mts", "*.cts"],
+			"linter": {
+				"rules": {
+					"correctness": {
+						"noConstAssign": "off",
+						"noGlobalObjectCalls": "off",
+						"noInvalidConstructorSuper": "off",
+						"noInvalidNewBuiltin": "off",
+						"noNewSymbol": "off",
+						"noSetterReturn": "off",
+						"noUndeclaredVariables": "off",
+						"noUnreachable": "off",
+						"noUnreachableSuper": "off"
+					},
+					"style": {
+						"noArguments": "error",
+						"noVar": "error",
+						"useConst": "error"
+					},
+					"suspicious": {
+						"noDuplicateClassMembers": "off",
+						"noDuplicateObjectKeys": "off",
+						"noDuplicateParameters": "off",
+						"noFunctionAssign": "off",
+						"noImportAssign": "off",
+						"noRedeclare": "off",
+						"noUnsafeNegation": "off",
+						"useGetterReturn": "off"
+					}
+				}
+			}
+		}
+	]
+}
diff --git a/packages/backend/package.json b/packages/backend/package.json
index 1b4f04f20b..3b5dea1e96 100644
--- a/packages/backend/package.json
+++ b/packages/backend/package.json
@@ -22,6 +22,9 @@
 		"typecheck": "tsc --noEmit",
 		"eslint": "eslint --quiet \"src/**/*.ts\"",
 		"lint": "pnpm typecheck && pnpm eslint",
+		"biome-lint": "pnpm typecheck && pnpm biome lint",
+		"format": "pnpm biome format",
+		"format:write": "pnpm biome format --write",
 		"jest": "cross-env NODE_ENV=test node --experimental-vm-modules --experimental-import-meta-resolve node_modules/jest/bin/jest.js --forceExit --config jest.config.unit.cjs",
 		"jest:e2e": "cross-env NODE_ENV=test node --experimental-vm-modules --experimental-import-meta-resolve node_modules/jest/bin/jest.js --forceExit --config jest.config.e2e.cjs",
 		"jest-and-coverage": "cross-env NODE_ENV=test node --experimental-vm-modules --experimental-import-meta-resolve node_modules/jest/bin/jest.js --coverage --forceExit --config jest.config.unit.cjs",
@@ -192,6 +195,7 @@
 		"xev": "3.0.2"
 	},
 	"devDependencies": {
+		"@biomejs/biome": "1.9.3",
 		"@jest/globals": "29.7.0",
 		"@nestjs/platform-express": "10.4.3",
 		"@simplewebauthn/types": "10.0.0",
diff --git a/packages/cherrypick-js/biome.json b/packages/cherrypick-js/biome.json
new file mode 100644
index 0000000000..fae2bf52ce
--- /dev/null
+++ b/packages/cherrypick-js/biome.json
@@ -0,0 +1,126 @@
+{
+	"$schema": "https://biomejs.dev/schemas/1.8.3/schema.json",
+	"organizeImports": { "enabled": true },
+	"linter": {
+		"enabled": true,
+		"rules": {
+			"recommended": false,
+			"complexity": {
+				"noBannedTypes": "error",
+				"noExtraBooleanCast": "error",
+				"noMultipleSpacesInRegularExpressionLiterals": "error",
+				"noUselessCatch": "error",
+				"noUselessTypeConstraint": "error",
+				"noWith": "error"
+			},
+			"correctness": {
+				"noConstAssign": "error",
+				"noConstantCondition": "warn",
+				"noEmptyCharacterClassInRegex": "error",
+				"noEmptyPattern": "warn",
+				"noGlobalObjectCalls": "error",
+				"noInnerDeclarations": "off",
+				"noInvalidConstructorSuper": "error",
+				"noNewSymbol": "error",
+				"noNonoctalDecimalEscape": "error",
+				"noPrecisionLoss": "error",
+				"noSelfAssign": "error",
+				"noSetterReturn": "error",
+				"noSwitchDeclarations": "error",
+				"noUndeclaredVariables": "error",
+				"noUnreachable": "error",
+				"noUnreachableSuper": "error",
+				"noUnsafeFinally": "error",
+				"noUnsafeOptionalChaining": "error",
+				"noUnusedLabels": "error",
+				"noUnusedVariables": "error",
+				"useArrayLiterals": "off",
+				"useIsNan": "error",
+				"useValidForDirection": "error",
+				"useYield": "error"
+			},
+			"style": {
+				"noDefaultExport": "warn",
+				"noInferrableTypes": "warn",
+				"noNamespace": "error",
+				"noNonNullAssertion": "warn",
+				"noParameterAssign": "warn",
+				"noVar": "error",
+				"useAsConstAssertion": "error"
+			},
+			"suspicious": {
+				"noAsyncPromiseExecutor": "off",
+				"noCatchAssign": "error",
+				"noClassAssign": "error",
+				"noCompareNegZero": "error",
+				"noControlCharactersInRegex": "warn",
+				"noDebugger": "error",
+				"noDoubleEquals": "error",
+				"noDuplicateCase": "error",
+				"noDuplicateClassMembers": "error",
+				"noDuplicateObjectKeys": "error",
+				"noDuplicateParameters": "error",
+				"noEmptyBlockStatements": "off",
+				"noExplicitAny": "warn",
+				"noExtraNonNullAssertion": "error",
+				"noFallthroughSwitchClause": "error",
+				"noFunctionAssign": "error",
+				"noGlobalAssign": "error",
+				"noImportAssign": "error",
+				"noMisleadingCharacterClass": "error",
+				"noMisleadingInstantiator": "error",
+				"noPrototypeBuiltins": "error",
+				"noRedeclare": "error",
+				"noShadowRestrictedNames": "error",
+				"noUnsafeDeclarationMerging": "error",
+				"noUnsafeNegation": "error",
+				"useGetterReturn": "error",
+				"useValidTypeof": "error"
+			}
+		},
+		"ignore": [
+			"**/node_modules",
+			"built",
+			"coverage",
+			"jest.config.ts",
+			"test",
+			"test-d",
+			"generator"
+		]
+	},
+	"overrides": [
+		{
+			"include": ["*.ts", "*.tsx"],
+			"linter": {
+				"rules": {
+					"correctness": {
+						"noConstAssign": "off",
+						"noGlobalObjectCalls": "off",
+						"noInvalidConstructorSuper": "off",
+						"noInvalidNewBuiltin": "off",
+						"noNewSymbol": "off",
+						"noSetterReturn": "off",
+						"noUndeclaredVariables": "off",
+						"noUnreachable": "off",
+						"noUnreachableSuper": "off"
+					},
+					"style": {
+						"noArguments": "error",
+						"noVar": "error",
+						"useConst": "error"
+					},
+					"suspicious": {
+						"noDuplicateClassMembers": "off",
+						"noDuplicateObjectKeys": "off",
+						"noDuplicateParameters": "off",
+						"noFunctionAssign": "off",
+						"noImportAssign": "off",
+						"noRedeclare": "off",
+						"noUnsafeNegation": "off",
+						"useGetterReturn": "off"
+					}
+				}
+			}
+		}
+	]
+}
diff --git a/packages/cherrypick-js/package.json b/packages/cherrypick-js/package.json
index 6152b1f802..3f1a04eff8 100644
--- a/packages/cherrypick-js/package.json
+++ b/packages/cherrypick-js/package.json
@@ -26,6 +26,9 @@
 		"eslint": "eslint './**/*.{js,jsx,ts,tsx}'",
 		"typecheck": "tsc --noEmit",
 		"lint": "pnpm typecheck && pnpm eslint",
+		"biome-lint": "pnpm typecheck && pnpm biome lint",
+		"format": "pnpm biome format",
+		"format:write": "pnpm biome format --write",
 		"jest": "jest --coverage --detectOpenHandles",
 		"test": "pnpm jest && pnpm tsd",
 		"update-autogen-code": "pnpm --filter cherrypick-js-type-generator generate && ncp generator/built/autogen src/autogen"
@@ -36,6 +39,7 @@
 		"directory": "packages/cherrypick-js"
 	},
 	"devDependencies": {
+		"@biomejs/biome": "1.9.3",
 		"@microsoft/api-extractor": "7.47.9",
 		"@swc/jest": "0.2.36",
 		"@types/jest": "29.5.13",
diff --git a/packages/frontend-embed/biome.json b/packages/frontend-embed/biome.json
new file mode 100644
index 0000000000..3867749276
--- /dev/null
+++ b/packages/frontend-embed/biome.json
@@ -0,0 +1,12 @@
+{
+	"$schema": "https://biomejs.dev/schemas/1.8.3/schema.json",
+	"organizeImports": {
+		"enabled": true
+	},
+	"linter": {
+		"enabled": true,
+		"rules": {
+			"recommended": true
+		}
+	}
+}
diff --git a/packages/frontend-embed/package.json b/packages/frontend-embed/package.json
index fe9602a6a1..86fcdf0d81 100644
--- a/packages/frontend-embed/package.json
+++ b/packages/frontend-embed/package.json
@@ -8,7 +8,10 @@
 		"build": "vite build",
 		"typecheck": "vue-tsc --noEmit",
 		"eslint": "eslint --quiet \"src/**/*.{ts,vue}\"",
-		"lint": "pnpm typecheck && pnpm eslint"
+		"lint": "pnpm typecheck && pnpm eslint",
+		"biome-lint": "pnpm typecheck && pnpm biome lint",
+		"format": "pnpm biome format",
+		"format:write": "pnpm biome format --write"
 	},
 	"dependencies": {
 		"@discordapp/twemoji": "15.1.0",
@@ -39,6 +42,7 @@
 		"vue": "3.5.10"
 	},
 	"devDependencies": {
+		"@biomejs/biome": "1.9.3",
 		"@misskey-dev/summaly": "5.1.0",
 		"@testing-library/vue": "8.1.0",
 		"@types/estree": "1.0.6",
diff --git a/packages/frontend-shared/biome.json b/packages/frontend-shared/biome.json
new file mode 100644
index 0000000000..3867749276
--- /dev/null
+++ b/packages/frontend-shared/biome.json
@@ -0,0 +1,12 @@
+{
+	"$schema": "https://biomejs.dev/schemas/1.8.3/schema.json",
+	"organizeImports": {
+		"enabled": true
+	},
+	"linter": {
+		"enabled": true,
+		"rules": {
+			"recommended": true
+		}
+	}
+}
diff --git a/packages/frontend-shared/package.json b/packages/frontend-shared/package.json
index f103bba896..1ac222924c 100644
--- a/packages/frontend-shared/package.json
+++ b/packages/frontend-shared/package.json
@@ -18,9 +18,13 @@
 		"watch": "nodemon -w package.json -e json --exec \"node ./build.js --watch\"",
 		"eslint": "eslint './**/*.{js,jsx,ts,tsx}'",
 		"typecheck": "tsc --noEmit",
-		"lint": "pnpm typecheck && pnpm eslint"
+		"lint": "pnpm typecheck && pnpm eslint",
+		"biome-lint": "pnpm typecheck && pnpm biome lint",
+		"format": "pnpm biome format",
+		"format:write": "pnpm biome format --write"
 	},
 	"devDependencies": {
+		"@biomejs/biome": "1.9.3",
 		"@types/node": "20.14.12",
 		"@typescript-eslint/eslint-plugin": "7.17.0",
 		"@typescript-eslint/parser": "7.17.0",
diff --git a/packages/frontend/biome.json b/packages/frontend/biome.json
new file mode 100644
index 0000000000..3867749276
--- /dev/null
+++ b/packages/frontend/biome.json
@@ -0,0 +1,12 @@
+{
+	"$schema": "https://biomejs.dev/schemas/1.8.3/schema.json",
+	"organizeImports": {
+		"enabled": true
+	},
+	"linter": {
+		"enabled": true,
+		"rules": {
+			"recommended": true
+		}
+	}
+}
diff --git a/packages/frontend/package.json b/packages/frontend/package.json
index f477b6002c..173abe2c93 100644
--- a/packages/frontend/package.json
+++ b/packages/frontend/package.json
@@ -14,7 +14,10 @@
 		"test-and-coverage": "vitest --run --coverage --globals",
 		"typecheck": "vue-tsc --noEmit",
 		"eslint": "eslint --quiet \"src/**/*.{ts,vue}\"",
-		"lint": "pnpm typecheck && pnpm eslint"
+		"lint": "pnpm typecheck && pnpm eslint",
+		"biome-lint": "pnpm typecheck && pnpm biome lint",
+		"format": "pnpm biome format",
+		"format:write": "pnpm biome format --write"
 	},
 	"dependencies": {
 		"@dice-roller/rpg-dice-roller": "^5.5.0",
@@ -84,6 +87,7 @@
 		"vuedraggable": "next"
 	},
 	"devDependencies": {
+		"@biomejs/biome": "1.9.3",
 		"@misskey-dev/summaly": "5.1.0",
 		"@storybook/addon-actions": "8.3.3",
 		"@storybook/addon-essentials": "8.3.3",
diff --git a/packages/misskey-bubble-game/biome.json b/packages/misskey-bubble-game/biome.json
new file mode 100644
index 0000000000..b2eaad8ca9
--- /dev/null
+++ b/packages/misskey-bubble-game/biome.json
@@ -0,0 +1,126 @@
+{
+	"$schema": "https://biomejs.dev/schemas/1.8.3/schema.json",
+	"organizeImports": { "enabled": true },
+	"linter": {
+		"enabled": true,
+		"rules": {
+			"recommended": false,
+			"complexity": {
+				"noBannedTypes": "error",
+				"noExtraBooleanCast": "error",
+				"noMultipleSpacesInRegularExpressionLiterals": "error",
+				"noUselessCatch": "error",
+				"noUselessTypeConstraint": "error",
+				"noWith": "error"
+			},
+			"correctness": {
+				"noConstAssign": "error",
+				"noConstantCondition": "warn",
+				"noEmptyCharacterClassInRegex": "error",
+				"noEmptyPattern": "warn",
+				"noGlobalObjectCalls": "error",
+				"noInnerDeclarations": "off",
+				"noInvalidConstructorSuper": "error",
+				"noNewSymbol": "error",
+				"noNonoctalDecimalEscape": "error",
+				"noPrecisionLoss": "error",
+				"noSelfAssign": "error",
+				"noSetterReturn": "error",
+				"noSwitchDeclarations": "error",
+				"noUndeclaredVariables": "error",
+				"noUnreachable": "error",
+				"noUnreachableSuper": "error",
+				"noUnsafeFinally": "error",
+				"noUnsafeOptionalChaining": "error",
+				"noUnusedLabels": "error",
+				"noUnusedVariables": "error",
+				"useArrayLiterals": "off",
+				"useIsNan": "error",
+				"useValidForDirection": "error",
+				"useYield": "error"
+			},
+			"style": {
+				"noDefaultExport": "warn",
+				"noInferrableTypes": "warn",
+				"noNamespace": "error",
+				"noNonNullAssertion": "warn",
+				"noParameterAssign": "warn",
+				"noVar": "error",
+				"useAsConstAssertion": "error"
+			},
+			"suspicious": {
+				"noAsyncPromiseExecutor": "off",
+				"noCatchAssign": "error",
+				"noClassAssign": "error",
+				"noCompareNegZero": "error",
+				"noControlCharactersInRegex": "warn",
+				"noDebugger": "error",
+				"noDoubleEquals": "error",
+				"noDuplicateCase": "error",
+				"noDuplicateClassMembers": "error",
+				"noDuplicateObjectKeys": "error",
+				"noDuplicateParameters": "error",
+				"noEmptyBlockStatements": "off",
+				"noExplicitAny": "warn",
+				"noExtraNonNullAssertion": "error",
+				"noFallthroughSwitchClause": "error",
+				"noFunctionAssign": "error",
+				"noGlobalAssign": "error",
+				"noImportAssign": "error",
+				"noMisleadingCharacterClass": "error",
+				"noMisleadingInstantiator": "error",
+				"noPrototypeBuiltins": "error",
+				"noRedeclare": "error",
+				"noShadowRestrictedNames": "error",
+				"noUnsafeDeclarationMerging": "error",
+				"noUnsafeNegation": "error",
+				"useGetterReturn": "error",
+				"useValidTypeof": "error"
+			}
+		},
+		"ignore": [
+			"**/node_modules",
+			"built",
+			"coverage",
+			"jest.config.ts",
+			"test",
+			"test-d"
+		]
+	},
+	"javascript": { "globals": [] },
+	"overrides": [
+		{
+			"include": ["**/*.ts", "**/*.tsx"],
+			"linter": {
+				"rules": {
+					"correctness": {
+						"noConstAssign": "off",
+						"noGlobalObjectCalls": "off",
+						"noInvalidConstructorSuper": "off",
+						"noInvalidNewBuiltin": "off",
+						"noNewSymbol": "off",
+						"noSetterReturn": "off",
+						"noUndeclaredVariables": "off",
+						"noUnreachable": "off",
+						"noUnreachableSuper": "off"
+					},
+					"style": {
+						"noArguments": "error",
+						"noVar": "error",
+						"useConst": "error"
+					},
+					"suspicious": {
+						"noDuplicateClassMembers": "off",
+						"noDuplicateObjectKeys": "off",
+						"noDuplicateParameters": "off",
+						"noFunctionAssign": "off",
+						"noImportAssign": "off",
+						"noRedeclare": "off",
+						"noUnsafeNegation": "off",
+						"useGetterReturn": "off"
+					}
+				}
+			}
+		}
+	]
+}
diff --git a/packages/misskey-bubble-game/package.json b/packages/misskey-bubble-game/package.json
index 528eb00b74..e579c171b0 100644
--- a/packages/misskey-bubble-game/package.json
+++ b/packages/misskey-bubble-game/package.json
@@ -19,9 +19,13 @@
 		"watch": "nodemon -w package.json -e json --exec \"node ./build.js --watch\"",
 		"eslint": "eslint './**/*.{js,jsx,ts,tsx}'",
 		"typecheck": "tsc --noEmit",
-		"lint": "pnpm typecheck && pnpm eslint"
+		"lint": "pnpm typecheck && pnpm eslint",
+		"biome-lint": "pnpm typecheck && pnpm biome lint",
+		"format": "pnpm biome format",
+		"format:write": "pnpm biome format --write"
 	},
 	"devDependencies": {
+		"@biomejs/biome": "1.9.3",
 		"@types/matter-js": "0.19.6",
 		"@types/seedrandom": "3.0.8",
 		"@types/node": "20.11.5",
diff --git a/packages/misskey-reversi/biome.json b/packages/misskey-reversi/biome.json
new file mode 100644
index 0000000000..9b1d735681
--- /dev/null
+++ b/packages/misskey-reversi/biome.json
@@ -0,0 +1,122 @@
+{
+	"$schema": "https://biomejs.dev/schemas/1.8.3/schema.json",
+	"organizeImports": { "enabled": true },
+	"linter": {
+		"enabled": true,
+		"rules": {
+			"recommended": false,
+			"complexity": {
+				"noBannedTypes": "error",
+				"noExtraBooleanCast": "error",
+				"noMultipleSpacesInRegularExpressionLiterals": "error",
+				"noUselessCatch": "error",
+				"noUselessTypeConstraint": "error",
+				"noWith": "error"
+			},
+			"correctness": {
+				"noConstAssign": "error",
+				"noConstantCondition": "warn",
+				"noEmptyCharacterClassInRegex": "error",
+				"noEmptyPattern": "warn",
+				"noGlobalObjectCalls": "error",
+				"noInnerDeclarations": "off",
+				"noInvalidConstructorSuper": "error",
+				"noNewSymbol": "error",
+				"noNonoctalDecimalEscape": "error",
+				"noPrecisionLoss": "error",
+				"noSelfAssign": "error",
+				"noSetterReturn": "error",
+				"noSwitchDeclarations": "error",
+				"noUndeclaredVariables": "error",
+				"noUnreachable": "error",
+				"noUnreachableSuper": "error",
+				"noUnsafeFinally": "error",
+				"noUnsafeOptionalChaining": "error",
+				"noUnusedLabels": "error",
+				"noUnusedVariables": "error",
+				"useArrayLiterals": "off",
+				"useIsNan": "error",
+				"useValidForDirection": "error",
+				"useYield": "error"
+			},
+			"style": {
+				"noDefaultExport": "warn",
+				"noInferrableTypes": "warn",
+				"noNamespace": "error",
+				"noNonNullAssertion": "warn",
+				"noParameterAssign": "warn",
+				"noVar": "error",
+				"useAsConstAssertion": "error"
+			},
+			"suspicious": {
+				"noAsyncPromiseExecutor": "off",
+				"noCatchAssign": "error",
+				"noClassAssign": "error",
+				"noCompareNegZero": "error",
+				"noControlCharactersInRegex": "warn",
+				"noDebugger": "error",
+				"noDoubleEquals": "error",
+				"noDuplicateCase": "error",
+				"noDuplicateClassMembers": "error",
+				"noDuplicateObjectKeys": "error",
+				"noDuplicateParameters": "error",
+				"noEmptyBlockStatements": "off",
+				"noExplicitAny": "warn",
+				"noExtraNonNullAssertion": "error",
+				"noFallthroughSwitchClause": "error",
+				"noFunctionAssign": "error",
+				"noGlobalAssign": "error",
+				"noImportAssign": "error",
+				"noMisleadingCharacterClass": "error",
+				"noMisleadingInstantiator": "error",
+				"noPrototypeBuiltins": "error",
+				"noRedeclare": "error",
+				"noShadowRestrictedNames": "error",
+				"noUnsafeDeclarationMerging": "error",
+				"noUnsafeNegation": "error",
+				"useGetterReturn": "error",
+				"useValidTypeof": "error"
+			}
+		},
+		"ignore": [
+			"**/node_modules",
+			"built"
+		]
+	},
+	"javascript": { "globals": [] },
+	"overrides": [
+		{
+			"include": ["**/*.ts", "**/*.tsx"],
+			"linter": {
+				"rules": {
+					"correctness": {
+						"noConstAssign": "off",
+						"noGlobalObjectCalls": "off",
+						"noInvalidConstructorSuper": "off",
+						"noInvalidNewBuiltin": "off",
+						"noNewSymbol": "off",
+						"noSetterReturn": "off",
+						"noUndeclaredVariables": "off",
+						"noUnreachable": "off",
+						"noUnreachableSuper": "off"
+					},
+					"style": {
+						"noArguments": "error",
+						"noVar": "error",
+						"useConst": "error"
+					},
+					"suspicious": {
+						"noDuplicateClassMembers": "off",
+						"noDuplicateObjectKeys": "off",
+						"noDuplicateParameters": "off",
+						"noFunctionAssign": "off",
+						"noImportAssign": "off",
+						"noRedeclare": "off",
+						"noUnsafeNegation": "off",
+						"useGetterReturn": "off"
+					}
+				}
+			}
+		}
+	]
+}
diff --git a/packages/misskey-reversi/package.json b/packages/misskey-reversi/package.json
index c6db6e6221..bd7bd4a3e4 100644
--- a/packages/misskey-reversi/package.json
+++ b/packages/misskey-reversi/package.json
@@ -19,9 +19,13 @@
 		"watch": "nodemon -w package.json -e json --exec \"node ./build.js --watch\"",
 		"eslint": "eslint './**/*.{js,jsx,ts,tsx}'",
 		"typecheck": "tsc --noEmit",
-		"lint": "pnpm typecheck && pnpm eslint"
+		"lint": "pnpm typecheck && pnpm eslint",
+		"biome-lint": "pnpm typecheck && pnpm biome lint",
+		"format": "pnpm biome format",
+		"format:write": "pnpm biome format --write"
 	},
 	"devDependencies": {
+		"@biomejs/biome": "1.9.3",
 		"@types/node": "20.11.5",
 		"@typescript-eslint/eslint-plugin": "7.1.0",
 		"@typescript-eslint/parser": "7.1.0",
diff --git a/packages/sw/biome.json b/packages/sw/biome.json
new file mode 100644
index 0000000000..3157cd31ad
--- /dev/null
+++ b/packages/sw/biome.json
@@ -0,0 +1,119 @@
+{
+	"$schema": "https://biomejs.dev/schemas/1.8.3/schema.json",
+	"organizeImports": { "enabled": true },
+	"linter": {
+		"enabled": true,
+		"rules": {
+			"recommended": false,
+			"complexity": {
+				"noBannedTypes": "error",
+				"noExtraBooleanCast": "error",
+				"noMultipleSpacesInRegularExpressionLiterals": "error",
+				"noUselessCatch": "error",
+				"noUselessTypeConstraint": "error",
+				"noWith": "error"
+			},
+			"correctness": {
+				"noConstAssign": "error",
+				"noConstantCondition": "warn",
+				"noEmptyCharacterClassInRegex": "error",
+				"noEmptyPattern": "warn",
+				"noGlobalObjectCalls": "error",
+				"noInnerDeclarations": "off",
+				"noInvalidConstructorSuper": "error",
+				"noNewSymbol": "error",
+				"noNonoctalDecimalEscape": "error",
+				"noPrecisionLoss": "error",
+				"noSelfAssign": "error",
+				"noSetterReturn": "error",
+				"noSwitchDeclarations": "error",
+				"noUndeclaredVariables": "error",
+				"noUnreachable": "error",
+				"noUnreachableSuper": "error",
+				"noUnsafeFinally": "error",
+				"noUnsafeOptionalChaining": "error",
+				"noUnusedLabels": "error",
+				"noUnusedVariables": "error",
+				"useArrayLiterals": "off",
+				"useIsNan": "error",
+				"useValidForDirection": "error",
+				"useYield": "error"
+			},
+			"style": {
+				"noDefaultExport": "warn",
+				"noInferrableTypes": "warn",
+				"noNamespace": "error",
+				"noNonNullAssertion": "warn",
+				"noParameterAssign": "warn",
+				"noVar": "error",
+				"useAsConstAssertion": "error"
+			},
+			"suspicious": {
+				"noAsyncPromiseExecutor": "off",
+				"noCatchAssign": "error",
+				"noClassAssign": "error",
+				"noCompareNegZero": "error",
+				"noControlCharactersInRegex": "warn",
+				"noDebugger": "error",
+				"noDoubleEquals": "error",
+				"noDuplicateCase": "error",
+				"noDuplicateClassMembers": "error",
+				"noDuplicateObjectKeys": "error",
+				"noDuplicateParameters": "error",
+				"noEmptyBlockStatements": "off",
+				"noExplicitAny": "warn",
+				"noExtraNonNullAssertion": "error",
+				"noFallthroughSwitchClause": "error",
+				"noFunctionAssign": "error",
+				"noGlobalAssign": "error",
+				"noImportAssign": "error",
+				"noMisleadingCharacterClass": "error",
+				"noMisleadingInstantiator": "error",
+				"noPrototypeBuiltins": "error",
+				"noRedeclare": "error",
+				"noShadowRestrictedNames": "error",
+				"noUnsafeDeclarationMerging": "error",
+				"noUnsafeNegation": "error",
+				"useGetterReturn": "error",
+				"useValidTypeof": "error"
+			}
+		},
+		"ignore": ["build.js"]
+	},
+	"javascript": { "globals": [] },
+	"overrides": [
+		{
+			"include": ["**/*.ts", "**/*.tsx"],
+			"linter": {
+				"rules": {
+					"correctness": {
+						"noConstAssign": "off",
+						"noGlobalObjectCalls": "off",
+						"noInvalidConstructorSuper": "off",
+						"noInvalidNewBuiltin": "off",
+						"noNewSymbol": "off",
+						"noSetterReturn": "off",
+						"noUndeclaredVariables": "off",
+						"noUnreachable": "off",
+						"noUnreachableSuper": "off"
+					},
+					"style": {
+						"noArguments": "error",
+						"noVar": "error",
+						"useConst": "error"
+					},
+					"suspicious": {
+						"noDuplicateClassMembers": "off",
+						"noDuplicateObjectKeys": "off",
+						"noDuplicateParameters": "off",
+						"noFunctionAssign": "off",
+						"noImportAssign": "off",
+						"noRedeclare": "off",
+						"noUnsafeNegation": "off",
+						"useGetterReturn": "off"
+					}
+				}
+			}
+		}
+	]
+}
diff --git a/packages/sw/package.json b/packages/sw/package.json
index 35f55cda99..1b85d81e0a 100644
--- a/packages/sw/package.json
+++ b/packages/sw/package.json
@@ -6,7 +6,10 @@
 		"build": "node build.js",
 		"typecheck": "tsc --noEmit",
 		"eslint": "eslint --quiet src/**/*.ts",
-		"lint": "pnpm typecheck && pnpm eslint"
+		"lint": "pnpm typecheck && pnpm eslint",
+		"biome-lint": "pnpm typecheck && pnpm biome lint",
+		"format": "pnpm biome format",
+		"format:write": "pnpm biome format --write"
 	},
 	"dependencies": {
 		"esbuild": "0.23.1",
@@ -14,6 +17,7 @@
 		"cherrypick-js": "workspace:*"
 	},
 	"devDependencies": {
+		"@biomejs/biome": "1.9.3",
 		"@typescript-eslint/parser": "7.17.0",
 		"@typescript/lib-webworker": "npm:@types/serviceworker@0.0.67",
 		"eslint-plugin-import": "2.30.0",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index c28b31b6c3..b5b4da8530 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -50,6 +50,9 @@ importers:
         specifier: 4.4.0
         version: 4.4.0(encoding@0.1.13)
     devDependencies:
+      '@biomejs/biome':
+        specifier: 1.9.3
+        version: 1.9.3
       '@misskey-dev/eslint-plugin':
         specifier: 2.0.3
         version: 2.0.3(@eslint/compat@1.1.1)(@typescript-eslint/eslint-plugin@7.17.0(@typescript-eslint/parser@7.17.0(eslint@9.8.0)(typescript@5.6.2))(eslint@9.8.0)(typescript@5.6.2))(@typescript-eslint/parser@7.17.0(eslint@9.8.0)(typescript@5.6.2))(eslint-plugin-import@2.30.0(@typescript-eslint/parser@7.17.0(eslint@9.8.0)(typescript@5.6.2))(eslint@9.8.0))(eslint@9.8.0)(globals@15.9.0)
@@ -544,6 +547,9 @@ importers:
         specifier: 6.0.3
         version: 6.0.3
     devDependencies:
+      '@biomejs/biome':
+        specifier: 1.9.3
+        version: 1.9.3
       '@jest/globals':
         specifier: 29.7.0
         version: 29.7.0
@@ -713,6 +719,9 @@ importers:
         specifier: 4.4.0
         version: 4.4.0
     devDependencies:
+      '@biomejs/biome':
+        specifier: 1.9.3
+        version: 1.9.3
       '@microsoft/api-extractor':
         specifier: 7.47.9
         version: 7.47.9(@types/node@20.14.12)
@@ -993,6 +1002,9 @@ importers:
         specifier: next
         version: 4.1.0(vue@3.5.10(typescript@5.6.2))
     devDependencies:
+      '@biomejs/biome':
+        specifier: 1.9.3
+        version: 1.9.3
       '@misskey-dev/summaly':
         specifier: 5.1.0
         version: 5.1.0
@@ -1103,7 +1115,7 @@ importers:
         version: 7.17.0(eslint@9.8.0)(typescript@5.6.2)
       '@vitest/coverage-v8':
         specifier: 1.6.0
-        version: 1.6.0(vitest@1.6.0(@types/node@20.14.12)(happy-dom@10.0.3)(jsdom@24.1.1)(sass@1.79.3)(terser@5.33.0))
+        version: 1.6.0(vitest@1.6.0(@types/node@20.14.12)(happy-dom@10.0.3)(jsdom@24.1.1(bufferutil@4.0.7)(utf-8-validate@6.0.3))(sass@1.79.3)(terser@5.33.0))
       '@vue/runtime-core':
         specifier: 3.5.10
         version: 3.5.10
@@ -1172,7 +1184,7 @@ importers:
         version: 1.0.3
       vitest:
         specifier: 1.6.0
-        version: 1.6.0(@types/node@20.14.12)(happy-dom@10.0.3)(jsdom@24.1.1)(sass@1.79.3)(terser@5.33.0)
+        version: 1.6.0(@types/node@20.14.12)(happy-dom@10.0.3)(jsdom@24.1.1(bufferutil@4.0.7)(utf-8-validate@6.0.3))(sass@1.79.3)(terser@5.33.0)
       vitest-fetch-mock:
         specifier: 0.2.2
         version: 0.2.2(encoding@0.1.13)(vitest@1.6.0(@types/node@20.14.12)(happy-dom@10.0.3)(jsdom@24.1.1(bufferutil@4.0.7)(utf-8-validate@6.0.3))(sass@1.79.3)(terser@5.33.0))
@@ -1267,6 +1279,9 @@ importers:
         specifier: 3.5.10
         version: 3.5.10(typescript@5.6.2)
     devDependencies:
+      '@biomejs/biome':
+        specifier: 1.9.3
+        version: 1.9.3
       '@misskey-dev/summaly':
         specifier: 5.1.0
         version: 5.1.0
@@ -1302,7 +1317,7 @@ importers:
         version: 7.17.0(eslint@9.8.0)(typescript@5.6.2)
       '@vitest/coverage-v8':
         specifier: 1.6.0
-        version: 1.6.0(vitest@1.6.0(@types/node@20.14.12)(happy-dom@10.0.3)(jsdom@24.1.1)(sass@1.79.3)(terser@5.33.0))
+        version: 1.6.0(vitest@1.6.0(@types/node@20.14.12)(happy-dom@10.0.3)(jsdom@24.1.1(bufferutil@4.0.7)(utf-8-validate@6.0.3))(sass@1.79.3)(terser@5.33.0))
       '@vue/runtime-core':
         specifier: 3.5.10
         version: 3.5.10
@@ -1364,6 +1379,9 @@ importers:
         specifier: 3.4.37
         version: 3.4.37(typescript@5.5.4)
     devDependencies:
+      '@biomejs/biome':
+        specifier: 1.9.3
+        version: 1.9.3
       '@types/node':
         specifier: 20.14.12
         version: 20.14.12
@@ -1398,6 +1416,9 @@ importers:
         specifier: 3.0.5
         version: 3.0.5
     devDependencies:
+      '@biomejs/biome':
+        specifier: 1.9.3
+        version: 1.9.3
       '@types/matter-js':
         specifier: 0.19.6
         version: 0.19.6
@@ -1435,6 +1456,9 @@ importers:
         specifier: 1.2.2
         version: 1.2.2
     devDependencies:
+      '@biomejs/biome':
+        specifier: 1.9.3
+        version: 1.9.3
       '@types/node':
         specifier: 20.11.5
         version: 20.11.5
@@ -1472,6 +1496,9 @@ importers:
         specifier: 6.2.1
         version: 6.2.1
     devDependencies:
+      '@biomejs/biome':
+        specifier: 1.9.3
+        version: 1.9.3
       '@typescript-eslint/parser':
         specifier: 7.17.0
         version: 7.17.0(eslint@9.8.0)(typescript@5.6.2)
@@ -1916,6 +1943,59 @@ packages:
   '@bcoe/v8-coverage@0.2.3':
     resolution: {integrity: sha512-0hYQ8SB4Db5zvZB4axdMHGwEaQjkZzFjQiN9LVYvIFB2nSUHW9tYpxWriPrWDASIxiaXax83REcLxuSdnGPZtw==}
 
+  '@biomejs/biome@1.9.3':
+    resolution: {integrity: sha512-POjAPz0APAmX33WOQFGQrwLvlu7WLV4CFJMlB12b6ZSg+2q6fYu9kZwLCOA+x83zXfcPd1RpuWOKJW0GbBwLIQ==}
+    engines: {node: '>=14.21.3'}
+    hasBin: true
+
+  '@biomejs/cli-darwin-arm64@1.9.3':
+    resolution: {integrity: sha512-QZzD2XrjJDUyIZK+aR2i5DDxCJfdwiYbUKu9GzkCUJpL78uSelAHAPy7m0GuPMVtF/Uo+OKv97W3P9nuWZangQ==}
+    engines: {node: '>=14.21.3'}
+    cpu: [arm64]
+    os: [darwin]
+
+  '@biomejs/cli-darwin-x64@1.9.3':
+    resolution: {integrity: sha512-vSCoIBJE0BN3SWDFuAY/tRavpUtNoqiceJ5PrU3xDfsLcm/U6N93JSM0M9OAiC/X7mPPfejtr6Yc9vSgWlEgVw==}
+    engines: {node: '>=14.21.3'}
+    cpu: [x64]
+    os: [darwin]
+
+  '@biomejs/cli-linux-arm64-musl@1.9.3':
+    resolution: {integrity: sha512-VBzyhaqqqwP3bAkkBrhVq50i3Uj9+RWuj+pYmXrMDgjS5+SKYGE56BwNw4l8hR3SmYbLSbEo15GcV043CDSk+Q==}
+    engines: {node: '>=14.21.3'}
+    cpu: [arm64]
+    os: [linux]
+
+  '@biomejs/cli-linux-arm64@1.9.3':
+    resolution: {integrity: sha512-vJkAimD2+sVviNTbaWOGqEBy31cW0ZB52KtpVIbkuma7PlfII3tsLhFa+cwbRAcRBkobBBhqZ06hXoZAN8NODQ==}
+    engines: {node: '>=14.21.3'}
+    cpu: [arm64]
+    os: [linux]
+
+  '@biomejs/cli-linux-x64-musl@1.9.3':
+    resolution: {integrity: sha512-TJmnOG2+NOGM72mlczEsNki9UT+XAsMFAOo8J0me/N47EJ/vkLXxf481evfHLlxMejTY6IN8SdRSiPVLv6AHlA==}
+    engines: {node: '>=14.21.3'}
+    cpu: [x64]
+    os: [linux]
+
+  '@biomejs/cli-linux-x64@1.9.3':
+    resolution: {integrity: sha512-x220V4c+romd26Mu1ptU+EudMXVS4xmzKxPVb9mgnfYlN4Yx9vD5NZraSx/onJnd3Gh/y8iPUdU5CDZJKg9COA==}
+    engines: {node: '>=14.21.3'}
+    cpu: [x64]
+    os: [linux]
+
+  '@biomejs/cli-win32-arm64@1.9.3':
+    resolution: {integrity: sha512-lg/yZis2HdQGsycUvHWSzo9kOvnGgvtrYRgoCEwPBwwAL8/6crOp3+f47tPwI/LI1dZrhSji7PNsGKGHbwyAhw==}
+    engines: {node: '>=14.21.3'}
+    cpu: [arm64]
+    os: [win32]
+
+  '@biomejs/cli-win32-x64@1.9.3':
+    resolution: {integrity: sha512-cQMy2zanBkVLpmmxXdK6YePzmZx0s5Z7KEnwmrW54rcXK3myCNbQa09SwGZ8i/8sLw0H9F3X7K4rxVNGU8/D4Q==}
+    engines: {node: '>=14.21.3'}
+    cpu: [x64]
+    os: [win32]
+
   '@bull-board/api@6.0.0':
     resolution: {integrity: sha512-O0IsIwAOU47bPTJnqRO7RtKFQToMvwRebbuPi6M+SG1gXyiqixLg9pycnfXgSeroaT9E7QQ2PsCPW1HO8VORvw==}
     peerDependencies:
@@ -12876,6 +12956,41 @@ snapshots:
 
   '@bcoe/v8-coverage@0.2.3': {}
 
+  '@biomejs/biome@1.9.3':
+    optionalDependencies:
+      '@biomejs/cli-darwin-arm64': 1.9.3
+      '@biomejs/cli-darwin-x64': 1.9.3
+      '@biomejs/cli-linux-arm64': 1.9.3
+      '@biomejs/cli-linux-arm64-musl': 1.9.3
+      '@biomejs/cli-linux-x64': 1.9.3
+      '@biomejs/cli-linux-x64-musl': 1.9.3
+      '@biomejs/cli-win32-arm64': 1.9.3
+      '@biomejs/cli-win32-x64': 1.9.3
+
+  '@biomejs/cli-darwin-arm64@1.9.3':
+    optional: true
+
+  '@biomejs/cli-darwin-x64@1.9.3':
+    optional: true
+
+  '@biomejs/cli-linux-arm64-musl@1.9.3':
+    optional: true
+
+  '@biomejs/cli-linux-arm64@1.9.3':
+    optional: true
+
+  '@biomejs/cli-linux-x64-musl@1.9.3':
+    optional: true
+
+  '@biomejs/cli-linux-x64@1.9.3':
+    optional: true
+
+  '@biomejs/cli-win32-arm64@1.9.3':
+    optional: true
+
+  '@biomejs/cli-win32-x64@1.9.3':
+    optional: true
+
   '@bull-board/api@6.0.0(@bull-board/ui@6.0.0)':
     dependencies:
       '@bull-board/ui': 6.0.0
@@ -16489,7 +16604,7 @@ snapshots:
       vite: 5.4.8(@types/node@20.14.12)(sass@1.79.3)(terser@5.33.0)
       vue: 3.5.10(typescript@5.6.2)
 
-  '@vitest/coverage-v8@1.6.0(vitest@1.6.0(@types/node@20.14.12)(happy-dom@10.0.3)(jsdom@24.1.1)(sass@1.79.3)(terser@5.33.0))':
+  '@vitest/coverage-v8@1.6.0(vitest@1.6.0(@types/node@20.14.12)(happy-dom@10.0.3)(jsdom@24.1.1(bufferutil@4.0.7)(utf-8-validate@6.0.3))(sass@1.79.3)(terser@5.33.0))':
     dependencies:
       '@ampproject/remapping': 2.2.1
       '@bcoe/v8-coverage': 0.2.3
@@ -16504,7 +16619,7 @@ snapshots:
       std-env: 3.7.0
       strip-literal: 2.1.0
       test-exclude: 6.0.0
-      vitest: 1.6.0(@types/node@20.14.12)(happy-dom@10.0.3)(jsdom@24.1.1)(sass@1.79.3)(terser@5.33.0)
+      vitest: 1.6.0(@types/node@20.14.12)(happy-dom@10.0.3)(jsdom@24.1.1(bufferutil@4.0.7)(utf-8-validate@6.0.3))(sass@1.79.3)(terser@5.33.0)
     transitivePeerDependencies:
       - supports-color
 
@@ -24457,11 +24572,11 @@ snapshots:
   vitest-fetch-mock@0.2.2(encoding@0.1.13)(vitest@1.6.0(@types/node@20.14.12)(happy-dom@10.0.3)(jsdom@24.1.1(bufferutil@4.0.7)(utf-8-validate@6.0.3))(sass@1.79.3)(terser@5.33.0)):
     dependencies:
       cross-fetch: 3.1.5(encoding@0.1.13)
-      vitest: 1.6.0(@types/node@20.14.12)(happy-dom@10.0.3)(jsdom@24.1.1)(sass@1.79.3)(terser@5.33.0)
+      vitest: 1.6.0(@types/node@20.14.12)(happy-dom@10.0.3)(jsdom@24.1.1(bufferutil@4.0.7)(utf-8-validate@6.0.3))(sass@1.79.3)(terser@5.33.0)
     transitivePeerDependencies:
       - encoding
 
-  vitest@1.6.0(@types/node@20.14.12)(happy-dom@10.0.3)(jsdom@24.1.1)(sass@1.79.3)(terser@5.33.0):
+  vitest@1.6.0(@types/node@20.14.12)(happy-dom@10.0.3)(jsdom@24.1.1(bufferutil@4.0.7)(utf-8-validate@6.0.3))(sass@1.79.3)(terser@5.33.0):
     dependencies:
       '@vitest/expect': 1.6.0
       '@vitest/runner': 1.6.0