engrXiv (engineering archive) is dedicated to the dissemination of engineering knowledge quickly and efficiently.
TechRxiv (pronounced "tech archive") is an open, moderated preprint server for unpublished research in electrical engineering, computer science, and related technology.
CiteSeerx - Hosted by the College of Information Sciences and Technology at Penn State. CiteSeerx is an evolving scientific literature digital library and search engine that has focused primarily on the literature in computer and information science. CiteSeerx aims to improve the dissemination of scientific literature and to provide improvements in functionality, usability, availability, cost, comprehensiveness, efficiency, and timeliness in the access of scientific and scholarly knowledge.
Computing Research Repository (CoRR) - CoRR is part of the arXiv e-print service. Allows researchers to search, browse and download papers through its online repository. CoRR is available to all members of of the community at no charge. arXiv is owned and operated by Cornell University.