biome

Biome is one fast toolchain for the web, linting, formatting and sorting imports of JavaScript, TypeScript, JSX, TSX, JSON, CSS and GraphQL files with a single Rust binary. MegaLinter runs biome check, which applies lint rules, formatting checks and assist actions in a single pass.

Key Features:

• All-in-one toolchain: linter, formatter and import sorter in a single tool, replacing several separate dependencies
• Rust performance: checks large codebases in milliseconds
• Sensible defaults: hundreds of lint rules with recommended presets, most of them providing safe automatic fixes
• Formatter compatibility: about 97% compatibility with Prettier output
• Inline suppressions: granular control with // biome-ignore comments
• First-class monorepo support: nested configurations with extends and root detection

Activation: this linter runs only if a biome.json or biome.jsonc configuration file is found in your repository. Apply safe fixes automatically with APPLY_FIXES.

biome documentation

• Version in MegaLinter: 2.5.7
• Visit Official Web Site
• See How to configure biome rules
• See How to disable biome rules in files
• See Index of problems detected by biome

Configuration in MegaLinter

• Enable biome by adding CSS_BIOME in ENABLE_LINTERS variable
• Disable biome by adding CSS_BIOME in DISABLE_LINTERS variable

• Enable autofixes by adding CSS_BIOME in APPLY_FIXES variable

Variable	Description	Default value
CSS_BIOME_ARGUMENTS	User custom arguments to add in linter CLI call Ex: -s --foo "bar"
CSS_BIOME_COMMAND_REMOVE_ARGUMENTS	User custom arguments to remove from command line before calling the linter Ex: -s --foo "bar"
CSS_BIOME_FILTER_REGEX_INCLUDE	Custom regex including filter Ex: (src\|lib) ⚠️ Not available with CSS_BIOME_CLI_LINT_MODE = project	Exclude no file
CSS_BIOME_FILTER_REGEX_EXCLUDE	Custom regex excluding filter Ex: (test\|examples) ⚠️ Not available with CSS_BIOME_CLI_LINT_MODE = project	Exclude no file
CSS_BIOME_CLI_LINT_MODE	Override default CLI lint mode - file: Calls the linter for each file - list_of_files: Call the linter with the list of files as argument - project: Call the linter from the root of the project	list_of_files
CSS_BIOME_FORWARD_EXCLUDED_DIRECTORIES	In project CLI lint mode, forward excluded directories (EXCLUDED_DIRECTORIES + ADDITIONAL_EXCLUDED_DIRECTORIES) to the linter through its native exclusion arguments or generated ignore/config files	true
CSS_BIOME_FILE_EXTENSIONS	Allowed file extensions. "*" matches any extension, "" matches empty extension. Empty list excludes all files Ex: [".py", ""]	[".css"]
CSS_BIOME_FILE_NAMES_REGEX	File name regex filters. Regular expression list for filtering files by their base names using regex full match. Empty list includes all files Ex: ["Dockerfile(-.+)?", "Jenkinsfile"]	Include every file
CSS_BIOME_PRE_COMMANDS	List of bash commands to run before the linter	None
CSS_BIOME_POST_COMMANDS	List of bash commands to run after the linter	None
CSS_BIOME_UNSECURED_ENV_VARIABLES	List of env variables explicitly not filtered before calling CSS_BIOME and its pre/post commands	None
CSS_BIOME_CONFIG_FILE	biome configuration file name Use LINTER_DEFAULT to let the linter find it	biome.json
CSS_BIOME_RULES_PATH	Path where to find linter configuration file	Workspace folder, then MegaLinter default rules
CSS_BIOME_DISABLE_ERRORS	Run linter but consider errors as warnings	false
CSS_BIOME_DISABLE_ERRORS_IF_LESS_THAN	Maximum number of errors allowed	0
CSS_BIOME_TIMEOUT_SECONDS	Maximum duration in seconds of the linter run, after which the linter process and its child processes are killed and reported as an error (exit code 124). Overrides LINTER_TIMEOUT_SECONDS. 0 disables the timeout	300
CSS_BIOME_CLI_EXECUTABLE	Override CLI executable	['biome']

IDE Integration

Use biome in your favorite IDE to catch errors before MegaLinter !

	IDE	Extension Name	Install
	IDEA	Biome
	Visual Studio Code	Biome

MegaLinter Flavors

This linter is available in the following flavors

	Flavor	Description	Embedded linters	Info
	all	Default MegaLinter Flavor	131
	cupcake	MegaLinter for the most commonly used languages	98
	dotnetweb	Optimized for C, C++, C# or VB based projects with JS/TS	82
	javascript	Optimized for JAVASCRIPT or TYPESCRIPT based projects	69

Behind the scenes

How are identified applicable files

• Activated only if one of these files is found: biome.json, biome.jsonc
• File extensions: .css

How the linting is performed

biome is called once on the whole project directory (project CLI lint mode)

• filtering can not be done using MegaLinter configuration variables,it must be done using biome configuration or ignore file (if existing)
• VALIDATE_ALL_CODEBASE: false doesn't make biome analyze only updated files

Example calls

biome check myfile.css

biome check --config-path biome.json myfile.css

biome check --write myfile.css

Help content

Biome's command-line interface for checking, formatting, and linting files, managing configuration,
and interacting with the daemon.

Usage: biome COMMAND ...

Available options:
    -h, --help     Prints help information
    -V, --version  Prints version information

Available commands:
    version        Prints the Biome CLI version and information about the connected daemon server,
                   if any, then exits.
    upgrade        Upgrades Biome to the latest stable version.
    rage           Prints a troubleshooting report with CLI, platform, environment, configuration,
                   workspace, and daemon server information.
    start          Starts the Biome daemon server used for integration with third-party clients,
                   such as editor extensions.
    stop           Stops the Biome daemon server if it is running.
    check          Checks the specified files for formatting, linting, and assist actions.
    lint           Runs the linter on the specified files.
    format         Formats the specified files.
    ci             Runs formatting checks, linting checks, and assist actions in CI without
                   modifying files.
    init           Creates a default Biome configuration file in the current working directory.
    lsp-proxy      Ensures that the Biome daemon server is running, then forwards Language Server
                   Protocol messages between the daemon server and standard input and output.
    migrate        Previews configuration updates required by breaking changes. The `prettier` and
                   `eslint` subcommands instead import settings from those tools.
    search         Finds code that matches a GritQL pattern. This command is experimental.
    explain        Prints documentation for a lint rule or the path to the daemon server log
                   directory.
    clean          Removes the Biome daemon server log files.

Installation on mega-linter Docker image

• Dockerfile commands :

  # Parent descriptor install
  # renovate: datasource=npm depName=typescript
  ARG NPM_TYPESCRIPT_VERSION=6.0.3
  # Linter install
  # renovate: datasource=npm depName=@biomejs/biome
  ARG NPM_BIOMEJS_BIOME_VERSION=2.5.7
  

• NPM packages (node.js):
  • typescript@6.0.3
  • @biomejs/biome@2.5.7