Lots of such screen capture web service here:
What’s the best website screenshot capture API?
But instead of doing that by yourself, I think you should go with those many public link-shortening service, like t.co, because anti-malicious is already one of their purpose:
Having a link shortener protects users from malicious sites that
engage in spreading malware, phishing attacks, and other harmful
activity. A link converted by Twitter’s link service is checked
against a list of potentially dangerous sites. Users are warned with
the error message below when clicking on potentially harmful URLs.
solved Take screenshot via PHP and Javascript