PlayCanvas (https://playcanvas.com) is an open source 3D game engine that also offers a proprietary cloud-hosted creation platform. Although other game engines, such as Unity, offer WebGL support, PlayCanvas was built from the ground-up for the web. Additionally, PlayCanvas offers a wonderful development experience since it has many powerful features, such as a visual workspace, full WebGL 2 support, simultaneous editing from multiple computers, and more: