Verilator

The fastest free Verilog HDL simulator.

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Overview

Verilator is a high-performance, open-source Verilog and SystemVerilog simulator. It works by compiling synthesizable HDL code into a highly optimized C++ or SystemC model. This compiled model can then be linked with a C++ testbench, resulting in simulation speeds that are often significantly faster than traditional event-driven simulators. It is widely used for block-level verification and system-level modeling.

✨ Key Features

  • High-speed Verilog/SystemVerilog to C++/SystemC compilation
  • Support for synthesizable subset of SystemVerilog
  • Multithreaded simulation for parallel execution
  • Generates clean, human-readable C++ code
  • Support for code coverage analysis
  • Free and open source

🎯 Key Differentiators

  • Extremely high simulation performance due to its compiled-code approach
  • Completely free and open source, with an active development community
  • Excellent for integration into software-based verification environments

Unique Value: Provides the fastest available Verilog simulation speed, for free, by converting HDL designs into optimized, multithreaded C++ models.

🎯 Use Cases (5)

High-speed functional simulation of RTL blocks Architectural modeling and virtual prototyping Formal verification (as a backend for some tools) Running software on a simulated processor core Part of a CI/CD pipeline for automated testing

✅ Best For

  • Verification of open-source RISC-V processor cores
  • Simulation of large, cycle-accurate system models
  • Used in production environments at major semiconductor companies

💡 Check With Vendor

Verify these considerations match your specific requirements:

  • Simulation of non-synthesizable, event-driven testbenches
  • VHDL designs (Verilator does not support VHDL)
  • Users who require a full graphical debugging IDE

🏆 Alternatives

Siemens ModelSim/Questa Icarus Verilog Synopsys VCS Cadence Xcelium

Offers orders-of-magnitude faster simulation than event-driven simulators like Icarus Verilog or the free editions of commercial tools, at the cost of being limited to synthesizable constructs and requiring a C++ testbench.

💻 Platforms

Desktop (Linux, Windows via WSL/Cygwin, macOS)

✅ Offline Mode Available

🔌 Integrations

SystemC Makefiles and other build systems Cocotb

💰 Pricing

Contact for pricing
Free Tier Available

Free tier: Verilator is completely free and open source.

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