> ## Documentation Index
> Fetch the complete documentation index at: https://bun.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Catalogs

> Share common dependency versions across multiple packages in a monorepo

**Catalogs** share dependency versions across the packages in a monorepo. Rather than repeating the same versions in each workspace package, you define them once in the root `package.json` and reference them throughout your project.

## Overview

Instead of each workspace package specifying its own versions, you:

1. Define version catalogs in the root `package.json`
2. Reference those versions with the `catalog:` protocol
3. Update every package at once by changing the version in one place

This matters most in large monorepos where dozens of packages depend on the same versions of key dependencies.

## How to Use Catalogs

### Directory Structure Example

Consider a monorepo with the following structure:

```
my-monorepo/
├── package.json
├── bun.lock
└── packages/
    ├── app/
    │   └── package.json
    ├── ui/
    │   └── package.json
    └── utils/
        └── package.json
```

### 1. Define Catalogs in Root package.json

In your root-level `package.json`, add a `catalog` or `catalogs` field within the `workspaces` object:

```json package.json icon="file-json" theme={"theme":{"light":"github-light","dark":"dracula"}}
{
  "name": "my-monorepo",
  "workspaces": {
    "packages": ["packages/*"],
    "catalog": {
      "react": "^19.0.0",
      "react-dom": "^19.0.0"
    },
    "catalogs": {
      "testing": {
        "jest": "30.0.0",
        "testing-library": "14.0.0"
      }
    }
  }
}
```

`catalog` and `catalogs` also work at the top level of `package.json`.

### 2. Reference Catalog Versions in Workspace Packages

In your workspace packages, use the `catalog:` protocol to reference versions:

```json packages/app/package.json icon="file-json" theme={"theme":{"light":"github-light","dark":"dracula"}}
{
  "name": "app",
  "dependencies": {
    "react": "catalog:",
    "react-dom": "catalog:",
    "jest": "catalog:testing"
  }
}
```

```json packages/ui/package.json icon="file-json" theme={"theme":{"light":"github-light","dark":"dracula"}}
{
  "name": "ui",
  "dependencies": {
    "react": "catalog:",
    "react-dom": "catalog:"
  },
  "devDependencies": {
    "jest": "catalog:testing",
    "testing-library": "catalog:testing"
  }
}
```

### 3. Run Bun Install

Run `bun install` to install all dependencies according to the catalog versions.

## Catalog vs Catalogs

Bun supports two ways to define catalogs:

1. **`catalog`** (singular): A single default catalog for commonly used dependencies

   ```json package.json icon="file-json" theme={"theme":{"light":"github-light","dark":"dracula"}}
   "catalog": {
     "react": "^19.0.0",
     "react-dom": "^19.0.0"
   }
   ```

   Reference with `catalog:`:

   ```json packages/app/package.json icon="file-json" theme={"theme":{"light":"github-light","dark":"dracula"}}
   "dependencies": {
     "react": "catalog:"
   }
   ```

2. **`catalogs`** (plural): Multiple named catalogs for grouping dependencies

   ```json package.json icon="file-json" theme={"theme":{"light":"github-light","dark":"dracula"}}
   "catalogs": {
     "testing": {
       "jest": "30.0.0"
     },
     "ui": {
       "tailwind": "4.0.0"
     }
   }
   ```

   Reference with `catalog:<name>`:

   ```json packages/app/package.json icon="file-json" theme={"theme":{"light":"github-light","dark":"dracula"}}
   "dependencies": {
     "jest": "catalog:testing",
     "tailwind": "catalog:ui"
   }
   ```

## Benefits of Using Catalogs

* **Consistency**: All packages use the same version of critical dependencies
* **Maintenance**: Update a dependency version in one place instead of across multiple `package.json` files
* **Clarity**: Makes it obvious which dependencies are standardized across your monorepo
* **Simplicity**: No extra version resolution strategies or external tools

## Real-World Example

A larger example, for a React application:

**Root package.json**

```json package.json icon="file-json" theme={"theme":{"light":"github-light","dark":"dracula"}}
{
  "name": "react-monorepo",
  "workspaces": {
    "packages": ["packages/*"],
    "catalog": {
      "react": "^19.0.0",
      "react-dom": "^19.0.0",
      "react-router-dom": "^6.15.0"
    },
    "catalogs": {
      "build": {
        "webpack": "5.88.2",
        "babel": "7.22.10"
      },
      "testing": {
        "jest": "29.6.2",
        "react-testing-library": "14.0.0"
      }
    }
  },
  "devDependencies": {
    "typescript": "5.1.6"
  }
}
```

```json packages/app/package.json icon="file-json" theme={"theme":{"light":"github-light","dark":"dracula"}}
{
  "name": "app",
  "dependencies": {
    "react": "catalog:",
    "react-dom": "catalog:",
    "react-router-dom": "catalog:",
    "@monorepo/ui": "workspace:*",
    "@monorepo/utils": "workspace:*"
  },
  "devDependencies": {
    "webpack": "catalog:build",
    "babel": "catalog:build",
    "jest": "catalog:testing",
    "react-testing-library": "catalog:testing"
  }
}
```

```json packages/ui/package.json icon="file-json" theme={"theme":{"light":"github-light","dark":"dracula"}}
{
  "name": "@monorepo/ui",
  "dependencies": {
    "react": "catalog:",
    "react-dom": "catalog:"
  },
  "devDependencies": {
    "jest": "catalog:testing",
    "react-testing-library": "catalog:testing"
  }
}
```

```json packages/utils/package.json icon="file-json" theme={"theme":{"light":"github-light","dark":"dracula"}}
{
  "name": "@monorepo/utils",
  "dependencies": {
    "react": "catalog:"
  },
  "devDependencies": {
    "jest": "catalog:testing"
  }
}
```

## Updating Versions

To update versions across all packages, change the version in the root package.json:

```json package.json icon="file-json" theme={"theme":{"light":"github-light","dark":"dracula"}}
"catalog": {
  "react": "^19.1.0",  // Updated from ^19.0.0
  "react-dom": "^19.1.0"  // Updated from ^19.0.0
}
```

Then run `bun install` to update all packages.

## Lockfile Integration

Bun's lockfile tracks catalog versions, so installs are consistent across environments. The lockfile includes:

* The catalog definitions from your package.json
* The resolution of each cataloged dependency

```json bun.lock(excerpt) icon="file-json" theme={"theme":{"light":"github-light","dark":"dracula"}}
{
  "lockfileVersion": 2,
  "workspaces": {
    "": {
      "name": "react-monorepo",
    },
    "packages/app": {
      "name": "app",
      "dependencies": {
        "react": "catalog:",
        "react-dom": "catalog:",
        ...
      },
    },
    ...
  },
  "catalog": {
    "react": "^19.0.0",
    "react-dom": "^19.0.0",
    ...
  },
  "catalogs": {
    "build": {
      "webpack": "5.88.2",
      ...
    },
    ...
  },
  "packages": {
    ...
  }
}
```

## Limitations and Edge Cases

* Catalog references must match a dependency defined in either `catalog` or one of the named `catalogs`
* Empty strings and whitespace in catalog names are ignored (treated as default catalog)
* Invalid dependency versions in catalogs fail to resolve during `bun install`
* Catalogs are only available within workspaces; they cannot be used outside the monorepo

## Publishing

When you run `bun publish` or `bun pm pack`, Bun replaces `catalog:` references
in your `package.json` with the resolved version numbers. The published package
includes regular semver strings and no longer depends on your catalog
definitions.