pnpm Aliases

pnpm supports package aliases using the npm: protocol. This lets you install packages under different names, use multiple versions of the same package, or substitute packages.

Basic Syntax

pnpm add <alias>@npm:<package>@<version>

In package.json:

{
  "dependencies": {
    "<alias>": "npm:<package>@<version>"
  }
}

Use Cases

Multiple Versions of Same Package

Install different versions side by side:

{
  "dependencies": {
    "lodash3": "npm:lodash@3",
    "lodash4": "npm:lodash@4"
  }
}

Usage:

import lodash3 from 'lodash3'
import lodash4 from 'lodash4'

Replace Package with Fork

Substitute a package with a fork or alternative:

{
  "dependencies": {
    "original-pkg": "npm:my-fork@^1.0.0"
  }
}

All imports of original-pkg will resolve to my-fork.

Replace Deprecated Package

{
  "dependencies": {
    "request": "npm:@cypress/request@^3.0.0"
  }
}

Scoped to Unscoped (or vice versa)

{
  "dependencies": {
    "vue": "npm:@anthropic/vue@^3.0.0",
    "@myorg/utils": "npm:lodash@^4.17.21"
  }
}

CLI Usage

Add with alias

# Add lodash under alias
pnpm add lodash4@npm:lodash@4

# Add fork as original name
pnpm add request@npm:@cypress/request

Add multiple versions

pnpm add react17@npm:react@17 react18@npm:react@18

With TypeScript

For type resolution with aliases, you may need to configure TypeScript:

// tsconfig.json
{
  "compilerOptions": {
    "paths": {
      "lodash3": ["node_modules/lodash3"],
      "lodash4": ["node_modules/lodash4"]
    }
  }
}

Or use @types packages with aliases:

{
  "devDependencies": {
    "@types/lodash3": "npm:@types/lodash@3",
    "@types/lodash4": "npm:@types/lodash@4"
  }
}

Combined with Overrides

Force all transitive dependencies to use an alias:

# pnpm-workspace.yaml
overrides:
  "underscore": "npm:lodash@^4.17.21"

This replaces all underscore imports (including in dependencies) with lodash.

Git and Local Aliases

Aliases work with any valid pnpm specifier:

{
  "dependencies": {
    "my-fork": "npm:user/repo#commit",
    "local-pkg": "file:../local-package"
  }
}

Registry Aliases (namedRegistries)

Distinct from package aliases: a namedRegistries prefix selects *which registry* a package is fetched from.

```yaml title="pnpm-workspace.yaml" namedRegistries: work: https://npm.work.example.com/

pnpm add work:@corp/lib@^2.0.0 # resolves @corp/lib against the work registry

The built-in `gh:` alias points at GitHub Packages. Auth is reused from per-URL `.npmrc` entries.

## Best Practices

1. **Clear naming**: Use descriptive alias names that indicate purpose

"lodash-legacy": "npm:lodash@3" "lodash-modern": "npm:lodash@4"

2. **Document aliases**: explain why aliases exist

3. **Prefer overrides for global replacement**: to replace a package everywhere, use `overrides` (in `pnpm-workspace.yaml`) instead of aliases

4. **Test thoroughly**: Aliased packages may have subtle differences in behavior

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Source references:
- https://pnpm.io/aliases
- https://pnpm.io/settings#namedregistries
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