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Bun supports loading configuration options from .npmrc files, allowing you to reuse existing registry/scope configurations.
We recommend migrating your .npmrc file to Bun’s bunfig.toml format, as it provides more flexible options and can let you configure Bun-specific options.

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Supported options

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Set the default registry

The default registry is used to resolve packages, its default value is npm’s official registry (https://registry.npmjs.org/). To change it, you can set the registry option in .npmrc:
.npmrc
registry=http://localhost:4873/
The equivalent bunfig.toml option is install.registry:
bunfig.toml
install.registry = "http://localhost:4873/"

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Set the registry for a specific scope

@<scope>:registry allows you to set the registry for a specific scope:
.npmrc
@myorg:registry=http://localhost:4873/
The equivalent bunfig.toml option is to add a key in install.scopes:
bunfig.toml
[install.scopes]
myorg = "http://localhost:4873/"

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Configure options for a specific registry

//<registry_url>/:<key>=<value> allows you to set options for a specific registry:
.npmrc
# set an auth token for the registry
# ${...} is a placeholder for environment variables
//http://localhost:4873/:_authToken=${NPM_TOKEN}


# or you could set a username and password
# note that the password is base64 encoded
//http://localhost:4873/:username=myusername

//http://localhost:4873/:_password=${NPM_PASSWORD}

# or use _auth, which is your username and password
# combined into a single string, which is then base 64 encoded
//http://localhost:4873/:_auth=${NPM_AUTH}
The following options are supported:
  • _authToken
  • username
  • _password (base64 encoded password)
  • _auth (base64 encoded username:password, e.g. btoa(username + ":" + password))
The equivalent bunfig.toml option is to add a key in install.scopes:
bunfig.toml
[install.scopes]
myorg = { url = "http://localhost:4873/", username = "myusername", password = "$NPM_PASSWORD" }
Controls how workspace packages are installed when available locally:
.npmrc
link-workspace-packages=true
The equivalent bunfig.toml option is install.linkWorkspacePackages:
bunfig.toml
[install]
linkWorkspacePackages = true

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save-exact: Save exact versions

Always saves exact versions without the ^ prefix:
.npmrc
save-exact=true
The equivalent bunfig.toml option is install.exact:
bunfig.toml
[install]
exact = true