Follow the link to the site, then type in your favorite URL. The site will attempt to send the malformed Heartbeat request to your URL and report on what comes back.

For example, if you enter amazon.com, it will come back and say “All good, amazon.com seems fixed or unaffected!”

I tested a number of sites and found some that were straight-out susceptible and others that responded with messages such as “timeout” or “broken pipe”. To see what these mean, read the FAQ.

Big thanks to Filippo Valsorda for creating the test.