: A lightweight tool (only ~4MB) that is excellent for beginners. It features low-level gates and higher-level components like a Z80 microprocessor emulator. It can be found on SourceForge .

: A modern fork of the classic Logisim, this is arguably the most popular open-source tool for education. It supports complex components like FPGAs and VHDL and is available on the Logisim-evolution GitHub .

For learning on the go, several mobile apps provide robust simulation environments: Download - Logic Circuit

: For those needing professional-grade simulation, QSPICE is a new, high-performance tool from the creator of LTspice. It supports Verilog and C++ digital blocks and is available for free for Windows via Qorvo. Top Mobile Logic Simulators (Android/iOS)

: This open-source educational software features a clean, intuitive graphical interface for designing unrestricted circuit hierarchies with multi-bit buses. You can download it directly from the official LogicCircuit website .