Desmos 3D graphing calculator
Desmos is the best, free (as in cost) and easily accessible graphing calculator out there. I wish it was opensource though. I've even tried to make an alternative and it's really hard to match their functionality (or I'm just inexperienced). I hope an opensource alternative crops up.<p>Edit: Seems there has <a href="https://www.geogebra.org/" rel="nofollow noreferrer">https://www.geogebra.org/</a>