OpenLayers
Vector and raster maps with GL styles. Server side rendering by MapLibre GL Native. Map tile server for MapLibre GL JS, Android, iOS, Leaflet, OpenLayers, GIS via WMTS, etc.
Tegola is a Mapbox Vector Tile server written in Go
Cool extensions for Openlayers (ol) - animated clusters, CSS popup, Font Awesome symbol renderer, charts for statistical map (pie/bar), layer switcher, wikipedia layer, animations, canvas filters.
OpenLayers - Cesium integration
A library for drawing on maps that supports Mapbox, MapLibre, Google Maps, OpenLayers and Leaflet out the box
Modern GIS Web Client for JavaScript, based on Leaflet\OpenLayers\MapboxGL-JS\Classic(iClient8C), enhanced with ECharts\D3\MapV etc. Contributed by SuperMap & community.
The solution to create and share maps, dashboards, geostories with 3D support on the web. And it is open-source too!