How Biome works

Configuration

The configuration file is considered optional, Biome has good defaults. Use the configuration file to change those defaults.

The Biome configuration file is named biome.json and should be placed in the root directory of your project. The root directory is usually the directory containing your project’s package.json.

This configuration file enables the formatter and sets the preferred indent style and width. The linter is disabled:

biome.json

{
  "formatter": {
    "enabled": true,
    "indentStyle": "tab",
    "lineWidth": 120
  },
  "linter": {
    "enabled": false
  }
}

Default configuration

When you run biome init, the default configuration emitted is the following:

biome.json

{
  "organizeImports": { "enabled": true },
  "linter": {
    "enabled": true,
    "rules": { "recommended": true }
  }
}

Configuration file resolution

Biome uses auto discovery to find the nearest biome.json file. It starts looking for biome.json in the current working directory, and then it starts looking in the parent directories until:

• it finds a biome.json file;
• it applies Biome’s defaults if no biome.json is found;

Here’s an example:

└── app
    ├── backend
    │   ├── package.json
    │   └── biome.json
    └── frontend
        ├── legacy
        │   └── package.json
        ├── new
        │   └── package.json
        └── biome.json

• biome commands that run in app/backend/package.json will use the configuration file app/backend/biome.json;
• biome commands that run in app/frontend/legacy/package.json and app/frontend/new/package.json will use the configuration file app/frontend/biome.json;

Known Files

The following files are currently ignored by Biome. This means that no diagnostics will be ever emitted by Biome for those files.

• package.json
• package-lock.json
• npm-shrinkwrap.json
• yarn.lock
• composer.json
• composer.lock
• typescript.json
• tsconfig.json
• jsconfig.json
• deno.json
• deno.jsonc

The following files are parsed as JSON files with the options json.parser.allowComments and json.parser.allowTrailingCommas set to true. This is because editor tools like VSCode treat them like this.

• tslint.json
• babel.config.json
• .babelrc.json
• .ember-cli
• typedoc.json
• .eslintrc
• .eslintrc.json
• .jsfmtrc
• .jshintrc
• .swcrc
• .hintrc
• .babelrc