According to the JSHint website it is "an open-source project that is supported and maintained by the JavaScript developer community.".

However, the license still contains the following clause:

  "The Software shall be used for Good, not Evil."

So it is not using an OSI approved license, and a such I would not consider it open source. That clause adds a restriction on how you can use the software, and a very vague restriction too. Be wary if you intend to include this in an existing project.