VOSviewer
Created by Leiden University's CWTS, a software tool for constructing and visualizing bibliometric networks. Also offers text mining functionality that can be used to construct and visualize co-occurrence networks of important terms extracted from a body of scientific literature.
VosViewer also available in Dimensions for co-authorship analysis & citation analysis
biblioshiny
R package for bibliometrics
Publish or Perish
A free author and journal impact metrics software program developed by Anne Wil Harzing that retrieves and analyzes citations to articles and books. The software uses Google Scholar to obtain the raw citations. The tool can be used to locate most cited articles and books by searching in general citations field.