Bootstrap is the more common of the two in our index: it runs on 9,993 websites against 41 for PrimeVue, and 3 sites use both. Counts come from real scans, not vendor claims.
Bootstrap is a free and open-source CSS framework directed at responsive, mobile-first front-end web development. It contains CSS and JavaScript-based design templates for typography, forms, buttons, navigation, and other interface components.
PrimeVue is a rich set of open-source UI Components for Vue.js.
3 sites run both Bootstrap and PrimeVue. That is 7% of the sites using PrimeVue, the smaller of the two.
Want to know which one a particular site uses? Look it up and see its whole stack, or compare two sites side by side.