npm WARN package.json: No repository field

you can also mark the application as private if you don’t plan to put it in an actual repository.

{
  "name": "my-application",
  "version": "0.0.1",
  "private": true
}

It's just a check as of NPM v1.2.20, they report this as a warning.

However, don't worry, there are sooooooo many packages which still don't have the repository field in their package.json. The field is used for informational purposes.

In the case you're a package author, put the repository in your package.json, like this:

"repository": {
  "type": "git",
  "url": "git://github.com/username/repository.git"
}

Read more about the repository field, and see the logged bug for further details.

---

Additionally, as originally reported by @dan_nl, you can set private key in your package.json.
This will not only stop you from accidentally running npm publish in your app, but will also stop NPM from printing warnings regarding package.json problems.

{
  "name": "my-super-amazing-app",
  "version": "1.0.0",
  "private": true
}

If you are getting this from your own package.json, just add the repository field to it. (use the link to your actual repository):

"repository" : { 
   "type" : "git",
   "url" : "https://github.com/npm/npm.git"
 }

As dan_nl stated, you can add a private fake repository in package.json. You don't even need name and version for it:

{
  ...,
  "repository": {
    "private": true
  }
}

Update: This feature is undocumented and might not work. Choose the following option.

Better still: Set the private flag directly. This way npm doesn't ask for a README file either:

{
  "name": ...,
  "description": ...,
  "version": ...,
  "private": true
}