You may have seen something like the following code before in package.json and may be puzzled about the symbols like '<>~^'. Code: { "dependencies" : { "foo" : "1.0.0 - 2.9999.9999" , "bar" : ">=1.0.2 <2.1.2" , "baz" : ">1.0.2 <=2.3.4" , "boo" : "2.0.1" , "qux" : "<1.0.0 || >=2.3.1 <2.4.5 || >=2.5.2 <3.0.0" , "asd" : "http://asdf.com/asdf.tar.gz" , "til" : "~1.2" , "elf" : "~1.2.3" , "two" : "2.x" , "thr" : "3.3.x" , "lat" : "latest" , "dyl" : "file:../dyl" } } Here are the definitions I found in https://docs.npmjs.com/files/package.json . version Must match version exactly >version Must be greater than version >=version etc <version <=versi...