Chemix - Draw Lab Diagrams. Simply.
Chemix is a free online editor for drawing lab diagrams. Simple and intuitive, it is designed for students and pupils to help them draw diagrams of common laboratory equipment and lab setup of science experiments.
Mathcha - Online Math Editor
Online WYSIWYG Mathematics Editor (Equation Editor), fast and powerful Editing features, inputting Normal text, Math symbols, and drawing Graph/Diagram in one single editor, help writing Math Document much easier. Export to Latex, Tikz, SVG, or Image (PNG).
ChemDraw JS Sample Page