This tool is made up of a few subprograms. To begin, you could right click in the first program (Nand Lab) to add logic gates, inputs, and outputs. Afterwards, connect them. You can also browse logic gates in Gatepedia, and connect programs together in Connectron. In the future I am planning to add more programs, and ways to connect them.

Link: https://nandlab.itch.io/nandlab