Gazebo
Gazebo is a widely used open-source robotics simulator integrated with ROS, focusing on general robotics simulation without NVIDIA-specific GPU acceleration.
MuJoCo
MuJoCo specializes in physics simulation for robotics and biomechanics but lacks the integrated synthetic data generation and sensor simulation features of Isaac Sim.
Webots
Webots is a robot simulator supporting multiple robot types and sensors, with a focus on education and research, but does not provide NVIDIA Omniverse integration.
CoppeliaSim (V-REP)
CoppeliaSim offers versatile robot simulation with scripting and plugin support, but does not leverage NVIDIA GPU physics and ray-tracing.
Unity ML-Agents
Unity ML-Agents provides AI training environments with robotics simulation capabilities but is a general game engine platform rather than a dedicated robotics simulator.