MuJoCo vs 
Stable-Baselines3
MuJoCo vs Stable-Baselines3 compared for 2026 — features, license, ease of use, performance and which one to choose. The physics engine most robotics research runs on vs Reliable RL algorithms you can actually trust.
Updated regularly · curated by OpenSourceAI.tech
MuJoCo vs Stable-Baselines3 at a glance
| Spec | MuJoCo | Stable-Baselines3 |
|---|---|---|
| Category | Robotics & embodied AI | Robotics & embodied AI |
| Type | Physics simulator | RL algorithms |
| License | Apache-2.0 | MIT |
| Runs locally | Yes | Yes |
| Primary language | C++ | Python |
| Ease of use | Intermediate | Beginner |
| Best for | training control policies before touching real hardware | getting a working policy without reimplementing PPO from a paper |
| GitHub stars | 14.2k | 13.6k |
How MuJoCo and Stable-Baselines3 score
| Criterion | MuJoCo | Stable-Baselines3 |
|---|---|---|
| Popularity | 3.0 | 3.0 |
| Maintenance | 5.0 | 5.0 |
| Ease of use | 3.5 | 5.0 |
| Privacy | 5.0 | 5.0 |
| License freedom | 5.0 | 5.0 |
Scores are computed automatically from public signals — GitHub stars (popularity), recent commit activity (maintenance), license type (freedom), local-first design (privacy) and onboarding complexity (ease of use). Indicative, not a verdict.
What each one is
MuJoCo
MuJoCo simulates contact-rich dynamics fast and accurately. DeepMind open-sourced it, and it is now the default for reinforcement learning on robots.
- Accurate contact dynamics at very high speed
- Free since DeepMind released it
- The de-facto standard in RL papers
Stable-Baselines3
Stable-Baselines3 provides carefully tested PyTorch implementations of the main RL algorithms — PPO, SAC, TD3 — with sane defaults.
- Implementations verified against published results
- Excellent documentation
- Works out of the box with Gymnasium
Key differences
MuJoCo is physics simulator, while Stable-Baselines3 is rL algorithms. Their licenses differ (Apache-2.0 vs MIT), which matters if you ship a commercial product. MuJoCo leans more intermediate-friendly, whereas Stable-Baselines3 is more suited to beginner users. In short, MuJoCo fits training control policies before touching real hardware, and Stable-Baselines3 fits getting a working policy without reimplementing PPO from a paper.
Which should you choose?
Choose MuJoCo for training control policies before touching real hardware. Choose Stable-Baselines3 for getting a working policy without reimplementing PPO from a paper.
There is rarely one winner — many setups use both. The right pick depends on your hardware, your team's skills, and whether you value simplicity or control.
Frequently asked questions
Is MuJoCo or Stable-Baselines3 easier to use?
Stable-Baselines3 is generally the easier of the two to get started with, while MuJoCo rewards more setup with more control.
Are MuJoCo and Stable-Baselines3 free?
MuJoCo is free and open source (Apache-2.0), and Stable-Baselines3 is free and open source (MIT). Neither charges for the core software.
Can I run MuJoCo and Stable-Baselines3 locally?
MuJoCo: yes · Stable-Baselines3: yes. Both can be used without sending your data to a third-party cloud where their setup allows.
MuJoCo vs Stable-Baselines3 — which should I pick in 2026?
Choose MuJoCo for training control policies before touching real hardware. Choose Stable-Baselines3 for getting a working policy without reimplementing PPO from a paper.
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