The impact of Internet and Google like search engines radically influenced the information behavior of Net Generation users. They expect same environment in library services such that all their required information make available in a single set of results through unified search across all the available resources. Libraries have been striving to respond to this challenge for years. Until recently, federated search technology of the past decade was the better attempt in this area to meet these user expectations. But federated search solution is marked by the drawbacks of its slowness as it searches each database on the fly. New Generation cloud based Library Web scale discovery technology is a promising entrant in this landscape. This Paper attempts to provide a comprehensive overview of Library Web Scale Discovery solutions by depicting various facets of Web Scale Discovery solutions such as its importance to Library field, their possible role as the starting point for research, content coverage, and finally analyses the competition at the discovery front by comparing the services of major players. The comparative analysis shows that all the major service providers are extending competitive features and services, but varies in some areas and the adoption choice depends on the concerned library’s preferences and the cost involved.