Scheme-it | Free Online Schematic and Diagramming Tool Scheme-it is a free online schematic drawing tool that will allow you to produce professional looking schematic diagrams, add corresponding part numbers, and share your schematic with others. We have new features. Read about them in our What's New page under Help. Circuit Diagram - A Circuit Diagram Maker Circuit Diagram is a free application for making electronic circuit diagrams and exporting them as images. Design circuits online in your browser or using the desktop application.