MuJoCo

Multi-Joint dynamics with Contact — a fast and accurate physics simulator originally developed by Eman Todorov, now open-source under DeepMind. MuJoCo is the standard simulator for RL-based locomotion and manipulation research due to its speed, stability, and accurate contact modeling. It supports tendons, muscles, and soft contacts. MuJoCo 3 adds GPU-accelerated batch simulation (MJX).