CircuitLab is described as 'Sketch, simulate, and share your circuits, entirely in your browser -- no install required. Easy schematic capture and powerful SPICE-like, mixed-mode circuit simulation helps EE students, electronics hobbyists, and electrical engineers design faster' and is a circuit simulator in the education & reference category. There are more than 25 alternatives to CircuitLab, not only websites but also apps for a variety of platforms, including Windows, Linux, Mac and Flathub apps. The best CircuitLab alternative is KiCad, which is both free and Open Source. Other great sites and apps similar to CircuitLab are Fritzing, Circuit JS, EasyEDA and SimulIDE.