# bun why (/docs/pm/cli/why)

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Related: [bun publish](/docs/pm/cli/publish.md), [bun outdated](/docs/pm/cli/outdated.md), [bun audit](/docs/pm/cli/audit.md), [bun info](/docs/pm/cli/info.md)

`bun why` explains why a package is installed in your project by showing the dependency chain that led to it.

## Usage [#usage]

```bash terminal icon="terminal"
bun why <package>
```

## Arguments [#arguments]

* `<package>`: The name of the package to explain. Supports glob patterns like `@org/*` or `*-lodash`.

## Options [#options]

* `--top`: Show only the top-level dependencies instead of the complete dependency tree.
* `--depth <number>`: Maximum depth of the dependency tree to display.

## Examples [#examples]

Check why a specific package is installed:

```bash terminal icon="terminal"
bun why react
```

```txt
react@18.2.0
  └─ my-app@1.0.0 (requires ^18.0.0)
```

Check why all packages matching a pattern are installed:

```bash terminal icon="terminal"
bun why "@types/*"
```

```txt
@types/react@18.2.15
  └─ dev my-app@1.0.0 (requires ^18.0.0)

@types/react-dom@18.2.7
  └─ dev my-app@1.0.0 (requires ^18.0.0)
```

Show only top-level dependencies:

```bash terminal icon="terminal"
bun why express --top
```

```txt
express@4.18.2
  └─ my-app@1.0.0 (requires ^4.18.2)
```

Limit the dependency tree depth:

```bash terminal icon="terminal"
bun why express --depth 2
```

```txt
express@4.18.2
  └─ express-pollyfill@1.20.1 (requires ^4.18.2)
     └─ body-parser@1.20.1 (requires ^1.20.1)
     └─ accepts@1.3.8 (requires ^1.3.8)
        └─ (deeper dependencies hidden)
```

## Understanding the Output [#understanding-the-output]

The output shows:

* The package name and version being queried
* The dependency chain that led to its installation
* The type of dependency (dev, peer, optional, or production)
* The version requirement specified in each package's dependencies

For nested dependencies, the command shows the complete dependency tree by default, with indentation indicating the relationship hierarchy.