Celtic Explorer is a graphical user interface for rendering and manipulating Celtic knots on a rectangular grid. The application is web based and built on the HTML5 Canvas element and JavaScript.
I became interested in Celtic knots after seeing a YouTube video outlining the basic process for drawing them.
After drawing several knots, I wanted to get a computer to do the work of drawing for me, so that I could concentrate on understanding their structure. It took several years, and the popularization of the HTML5 Canvas element, but I finally figured how to programmatically draw Celtic knots in a web-based application.
Although the procedure for drawing Celtic knots is relatively simple, it's much harder to represent and formalize the algorithm. I first had to develop a formalism for represent Celtic knots, and then another to render them from this representation.
You can learn more about how to draw Celtic knots, how to represent them, and some more of my work at My Website.