There are various open source library management systems for libraries today. Comparing them with an aim of choosing one is not an easy task for many librarians. This is because since most of them share common functionalities at face value. The situation is more difficult in developing countries where most libraries and librarians might not have the necessary technical competence to critically evaluate the systems. The purpose of this paper is to show the similarities and differences of the architecture and functionalities of Koha and ABCD. This paper reviewed the existing literature and checked functionality of essential modules of Koha Version 3.12 and ABCD version 1.2. This was done with a view of identifying similarities, differences and unique features of the two software's. The review established that both ABCD and Koha have excellent functionalities in the essential modules for a library management system. Koha is Scalable and therefore can be used in any size of a library. They are both very good ‘free’ and customizable software's, however, one needs good capacity with the knowhow of the architecture and the languages used to be able to fully exploit the software full benefits of the software's.
Keywords: Koha, ABCD, LMS, Library management Systems, Library Automation