AR.js is an open source framework for three.js, and a-frame, enabling the creation of augmented reality apps / websites.
AR.js is an open-source lightweight Augmented Reality framework, coming with features like Image Tracking, Marker Tracking and Location based AR, and enabling the creation of apps and websites. It works great with its satellites three.js and aframe.io.
For anything related to AR.js - Efficient Augmented Reality for the Web.