Is there a service that lets me check a URL to see if it may possibly be a dangerous site?
When a user exits our application by clicking on an untrusted link, we sent them through a "are you sure you want to leave" redirection screen. It'd be a nice touch to do a quick check to see if we should warn the user as well.
Try with Google Safe Browsing API.
The Google Safe Browsing Lookup API is an experimental API that allows applications to check URLs against Google's constantly-updated lists of suspected phishing and malware pages.
You can use the Google Safe Browsing API to check if a URL is safe according to what they know about it. (API documentation)
How about z-protect.com?
Example report: http://www.z-protect.com/report/stackoverflow.com/ this system is using a dns server to block the pages ... maybe interessting?
An this service has a api! but with a limit of 10000 requests per day: http://www.z-protect.com/api
来源：https://stackoverflow.com/questions/7917747/service-to-check-a-url-for-malware-or-phishing