Custom NPM Registry

Using a Custom NPM Registry

The custom private npm registry setting makes it possible for Sandboxes in your workspace portal to retrieve npm packages from your own npm registry. You can access the settings here (opens in a new tab).


You can configure your private npm registry in your Team Settings (opens in a new tab).

Configuration Form

Registry Host

This can be either GitHub, npm or Custom. When choosing GitHub, we'll prefill the registry host with the GitHub Registry. When choosing npm, we'll prefill the host with the npm registry url. When choosing Custom you have the option to define the npm registry host yourself.

Auth Type

Npm supports two types of authentication: Basic and Bearer. More recent implementations use Bearer by default. You can see which type you need by looking at your .npmrc. If your .npmrc is showing something similar to this:


This means that you should use Basic auth. Artifactory often defaults to Basic auth.

If your .npmrc is showing something along the lines of this:


You need to opt for Bearer auth. Any configuration that uses _authToken needs Bearer auth.

Auth Token

This is the token that we'll use to connect to your registry. This token is encrypted and stored in our database using an external key, we also don't share this key with anyone else who has access to your sandbox. Read more about that here.

Specific Scopes

We only use your private registry for the packages that are behind specified scopes. For example, if you defined @acme as an enabled scope, we only use the registry to fetch packages that have this scope (like @acme/design-system). For all other packages we'll use the public registry.


It's important to us to keep the information and tokens of the npm registry private, because of this we've added some extra measures to ensure that nothing can leak.

Persisting Auth Token

The auth token is stored in our database in an encrypted form, using a key that's rolled and not available to the database itself. Even if our database would be compromised, your auth token would be encrypted and inaccessible.

Single-Sandbox Key

We never send the auth token to the browser. Instead, we give every editor of the sandbox a key that only gives them access to that specific sandbox. If they want to retrieve a package from the private npm registry, they will have to ask our API. The API will fetch the auth token, request the npm registry on behalf of the user and return the response to the user.

The advantage of this approach is that whenever you revoke access to an editor of the sandbox, they also won't have access to your private npm registry anymore. There's no need to re-roll tokens, as tokens are generated based on a sandbox-user combination.

Request structure of the custom registry implementation

Common Questions

Can I share a public sandbox with a private package?

No, we only enable private registries on sandboxes that are private. The main reason for this lies in the fact that we execute most sandboxes in the browser. Because of this, we need to download the npm dependencies to the browser to execute your code. If you would share a public sandbox containing a private package with someone, they would need to download that private package to execute the sandbox. Someone savvy enough would be able to extract the files from memory and read your private package in that case.

We want to prevent this from accidentally happening, which is why we only allow private sandboxes to have access to the private registry. If you do want to share a public sandbox containing a private package, you can add the .tgz to the sandbox and link to it from the package.json by referring to it as file:package-tar-name.tgz in the version field.

Our npm registry is behind a VPN, what can I do?

Since we use a proxy to access the npm registry, we don't support registries behind a VPN out of the box. However, we do have three solutions:

Solution 1: bypass the proxy We can bypass the proxy on our service to let the browser fetch from the registry directly. This is not enabled by default for everyone - please request this be turned on (opens in a new tab). The disadvantage of this approach is that you have to share your registry auth token with everyone who has access to the sandbox. Also, to make this work, you need to add CORS headers to your registry so the browser can fetch the packages directly from our origin.

Solution 2: whitelist the proxy Another solution is to whitelist the IP range of our proxy. We make sure that we keep the same IP for our proxy. Please request these details (opens in a new tab).

Solution 3: self-host the proxy A third option is to self-host the proxy in your network, and letting the proxy communicate with our API server to validate the tokens that are sent in. We can help get you setup with this (opens in a new tab).

Can I use a .npmrc file?

To make sure that credentials don't accidentally get shared with collaborators of a sandbox, we don't support reading credentials from a .npmrc file. We recommend you to put the auth token in the workspace configuration instead, so that it's encrypted and only shared with the admin of the workspace.

Does this work with container sandboxes?

Container Sandboxes are sandboxes that run on a Docker container instead of the browser. We're still working on adding support for private npm registries in our container sandboxes. To make private packages work in a container sandbox you could either drop the .tgz file manually in the sandbox, or use a .npmrc.