How to fix curl: (60) SSL certificate: Invalid certificate chain

Using the Safari browser (not Chrome, Firefox or Opera) on Mac OS X 10.9 (Mavericks) visit https://registry.npmjs.org

Click the Show certificate button and then check the checkbox labelled Always trust. Then click Continue and enter your password if required.

Curl should now work with that URL correctly.

First off, you should be wary of urls that throw SSL errors. That being said, you can suppress certificate errors in curl with

curl -k https://insecure.url/content-i-really-really-trust