ghdl

GHDL is a free and open‑source tool that analyzes, compiles, and simulates VHDL code conforming to the 2008, 1993 and 1987 standards, with experimental support for VHDL 2019. It provides a command‑line interface for running simulations, generating waveforms, and performing basic synthesis tasks. The project includes multiple back‑ends—LLVM, mcode and a deprecated GCC option—allowing just‑in‑time compilation and in‑memory code generation, and supports features such as IEEE operator handling, static expression evaluation, and signal dumping in FST format.

The software targets hardware designers, verification engineers, and educators who need a reliable VHDL simulator that can be integrated into build pipelines or used interactively. GHDL also offers experimental Python bindings (pyGHDL) for scripting and co‑simulation, as well as utilities for extracting design hierarchies, dependency graphs, and documentation from source comments.

Distinctive aspects include its cross‑platform availability (including macOS core support), a history of regular releases with incremental language and backend improvements, and the ability to run without generating external object files, which simplifies installation and execution.