Rated 3 out of 5 stars
The extension uses Filippo Valsorda's Heartbleed checker URL which seems to be common to most of the extensions of this type. But as the previous reviewer noted, it is unclear as to how confidential your browsing is if you install this addon.
To the developer, good idea but the notifications are too subtle.. the tiny icon is easy to miss. There should be some options for other ways of being notified such as a popup, overlay, or audible warning perhaps?