Accel-Sim - Simulation framework for simulating and validating programmable accelerators like GPUs
GPGPU Sim - GPGPU-Sim provides a detailed simulation model of a contemporary GPUs
FireSim - FireSim is an open-source cycle-accurate FPGA-accelerated full-system hardware simulation platform that runs on cloud FPGAs
MPGPUSim - MGPUSim is a Go based AMD GCN3 GPU simulator based-on the Akita framework.
SCALESim - SCALE sim is a CNN accelerator simulator, that provides cycle-accurate timing, power/energy, memory bandwidth and trace results for a specified accelerator configuration and neural network architecture.
STONNE - Simulation TOol of Neural Network Engines, a cycle-level, highly-modular and highly-extensible simulation framework that can plug into any high-level DNN framework as an accelerator device and perform end-to-end evaluation of flexible accelerator microarchitectures with sparsity support, running complete DNN models.
1.1.3. Micro-architecture/ISA simulators
ChampSim - ChampSim is a trace-based simulator for a microarchitecture study.
Mastik - A Micro-Architectural Side-Channel Toolkit
Venus - Venus is a RISC-V instruction set simulator built for education.
Ripes - Ripes is a visual computer architecture simulator and assembly code editor built for the RISC-V ISA.
WinMIPS64 - WinMIPS64 is an instruction set simulator, and is designed as a replacement for the popular Microsoft Windows utility WinDLX
Whisper - RISCV instruction set simulator (ISS) developed for the verification of the Swerv micro-controller. It allows the user to run RISCV code without RISCV hardware.
ARM Consistency Memory Model - The herd tool allows the user to execute the model with a specific question about the possible final states of the program using ARM consistency memory model.
MQSim - A Simulator for Modern NVMe and SATA SSDs
VAMPIRE - Variation-Aware model of Memory Power Informed by Real Experiments is an open-source DRAM power model based on an extensive experimental characterization of the power consumption of real DRAM modules.
RAMulator - Ramulator is a fast and cycle-accurate DRAM simulator  that supports a wide array of commercial, as well as academic, DRAM standards
Xyce - open source, SPICE-compatible, high-performance analog circuit simulator, capable of solving extremely large circuit problems by supporting large-scale parallel computing platforms.
Micro Cap 12 - Micro-Cap 12 is an integrated schematic editor and mixed analog/digital simulator that provides an interactive sketch and simulate environment for electronics engineers. Now Open Source.
Logisim - Logisim is an educational tool for designing and simulating digital logic circuits.
LogisimITA - An independently developed fork of logisim that's preferred by many
Logisim-Evolution - Another flavour of Logisim after the development of original version was stopped
Antares - Digital Circuit Learning Platform. A free, powerful platform for designing, simulating and explaining digital circuits
Verible - Verible is a suite of SystemVerilog developer tools, including a parser, style-linter, and formatter.
svinst - This tool takes a SystemVerilog file as input and produces as output the module(s) declared in that file, along with the module(s) instantiated in each one of those module declarations. It uses sv-parser and is adapted from svlint.