React

React revolutionized front-end development with its component-based model, driving the UIs of 40% of the top 10,000 websites since its 2013 release by Facebook (now Meta). With 10+ million weekly npm downloads and 200,000+ GitHub stars, it is the most starred UI library globally. React outperforms #4 on this list, Python, in web-specific developer adoption, as 25% more front-end projects choose React over alternatives like Vue or Angular.