1.shards （free） https://designrevision.com/demo/shards/
https://github.com/DesignRevision/shards-ui/releases
Shards is a modern design system based on Bootstrap 4 that comes packed with 10 extra custom components and two pre-built landing pages. It’s also lightweight with its stylesheet weighting only ~13kb minified and gzipped.
2.Now UI Kit PRO （pay) https://www.creative-tim.com/product/now-ui-kit-pro
3.unify （pay) https://wrapbootstrap.com/theme/unify-responsive-website-template-WB0412697
4.GitHub - tabler/tabler （free） Tabler is free and open-source HTML Dashboard UI Kit built on Bootstrap 4
5.Bootstrap4 Theme for nopCommerce (free) a new free starter theme for nopCommerce 4.0 which is based on Bootstrap 4 and looks same as default theme. .