Virtual learning environment (VLE) provides students a common platform where they can get the subject-wise tutorial online (and anytime), i.e. they are not limited to only class room teaching. Apart from making learning and teaching virtually real, VLEs are equipped with other features like syllabus/curriculum for the course; administrative information like location of sessions, details of prerequisites and co-requisites, credit information, notice board for up-to-date course information and how to get help, etc. Present paper is an effort to evaluate and compare the most widely used open source VLE software tools. It compares the features, pre-requisites, and other parameters based on the predetermined parameters. Ranks to all the four open source VLEs are given on the basis of comparative study.