There are many Free and Open Source Software (FOSS) available for library automation in the market and are being instrumental in managing information and knowledge all over the world. Cost effectiveness and the availability of source code are the major rationalities for LIS professionals to adopt FOSS over the proprietary packages. Open Source Integrated Library Management System (OSILMS) is gaining widespread adoption in Indian libraries for the last two decades. The present study intends to evaluate the perceptions of Indian LibSys software users on the adoption of OSILMS and focuses to survey the level of agreement of LibSys software users on some selected statements related to the features and characteristics of OSILMS. Study also compares the impact, functional features and financial aspects of OSILMS with its commercial counterparts practiced in Indian libraries. Online questionnaire method was used to collect the responses from the libraries in India using LibSys as their automation software. The study found that majority of the respondents positively agreed with most of the projected statements on the adeptness and rewards of OSILMS and a higher percentage of them expressed willingness to migrate to OSILMS.