A checker (site and tool) for CVE-2014-0160.
Public site at http://filippo.io/Heartbleed/
Tool usage: Heartbleed example.com:443
Exit codes: 0 - SAFE; 1 - VULNERABLE; 2 - ERROR. (recently changed)
Please note that the code is a bit of a mess, not exactly release-ready.
You will need Go 1.2.x, otherwise you get undefined: cipher.AEAD and other errors
go get github.com/FiloSottile/Heartbleed
go install github.com/FiloSottile/Heartbleed
You can also use docker to get a ready to run virtual machine with heartbleed, see https://github.com/kasimon/docker-heartbleed.