Gephi

Gephi is the premier open-source tool for network analysis — the kind of tool you use when you want to understand relationships, not just individual entities. It handles networks of tens of millions of nodes and edges, with algorithms for community detection, centrality measurement, and layout. For Indian researchers, Gephi enables analysis of social networks (who connects to whom in a community), organisational relationships (funding flows between donors and NGOs), trade networks (which states trade with which others), co-authorship patterns, and citation networks. The interactive visualisation makes patterns visible: clusters, bridges, hubs, and outliers jump out visually. Free, open-source, cross-platform, with an active plugin ecosystem.