Shimmy
An API conversion tool providing Gymnasium and PettingZoo bindings for popular external reinforcement learning environments.
Decision gist · record as of 2026-08-14
Yes. Shimmy is actively maintained, has no known vulnerabilities, uses a permissive MIT license, and solves a real fragmentation problem in RL development. Low install friction and support for current Python versions make it a practical choice for anyone integrating multiple RL environments.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Python 3.10 or later; numpy and gymnasium must be installed as runtime dependencies.
- Low friction installation as a pure-Python wheel.
- Actively maintained with a recent commit on 2026-08-08 and regular releases; the project is not archived and has accumulated 222 repository stars.
License · maintenance · safety
permissive license (permissive) — MIT license permits commercial and private use with minimal restrictions—you may use, modify, and distribute Shimmy freely provided you retain the license notice.
last release 2026-04-10 (126 days) · last repo commit 2026-08-08 · 222 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 250,994 downloads/mo, #8,603 on PyPI
Alternatives
Verify before relying
pip install shimmy
import shimmy
import gymnasium
# Shimmy provides bindings to wrap external RL environments
# for use with Gymnasium and PettingZoo APIs- Which specific external RL environments are currently supported by version 2.0.1
- Whether Shimmy handles environment state serialization or checkpointing
- Performance overhead of the API conversion layer compared to native environment calls
What it is and what it does
Shimmy is a bridge library that adapts external reinforcement learning environments to work with Gymnasium and PettingZoo, two popular standardized RL APIs. It solves the problem of environment fragmentation: RL researchers and practitioners often need to work with simulators built for different APIs, but want to use them within a modern, consistent framework. Shimmy wraps these external environments, translating their interfaces to match Gymnasium or PettingZoo conventions.
The package depends on numpy and gymnasium as its core runtime dependencies. It requires Python 3.10 or later and is actively maintained, with support for Python versions through 3.14. The library is designed for researchers, practitioners, and teams building RL agents who need to integrate multiple environment sources without rewriting integration code for each one.
Use it for
- Adapt a legacy Gym-based environment to work with modern Gymnasium code without rewriting your agent
- Use multiple third-party RL simulators within a single unified Gymnasium interface
- Integrate external multi-agent environments with PettingZoo for centralized agent training
- Build RL benchmarks that test agents across diverse environment sources without environment-specific glue code
- Migrate existing RL codebases from older APIs to Gymnasium by wrapping environments instead of refactoring
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
Shimmy is actively maintained, has no known vulnerabilities, uses a permissive MIT license, and solves a real fragmentation problem in RL development. Low install friction and support for current Python versions make it a practical choice for anyone integrating multiple RL environments.
Install
shimmy on PyPI
Before you install
Low friction installation as a pure-Python wheel. Actively maintained with a recent commit on 2026-08-08 and regular releases; the project is not archived and has accumulated 222 repository stars.
Requires Python 3.10 or later; numpy and gymnasium must be installed as runtime dependencies.
License in practice
MIT license permits commercial and private use with minimal restrictions—you may use, modify, and distribute Shimmy freely provided you retain the license notice.
Quickstart
pip install shimmy
import shimmy
import gymnasium
# Shimmy provides bindings to wrap external RL environments
# for use with Gymnasium and PettingZoo APIsVerify before relying
- Which specific external RL environments are currently supported by version 2.0.1
- Whether Shimmy handles environment state serialization or checkpointing
- Performance overhead of the API conversion layer compared to native environment calls
Package facts
| License | permissive license permissive |
| Python support | Supports the current Python release >=3.10 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 2 packagesnumpygymnasium |
| Maintenance | Actively maintained 126 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 250,994 / month, #8,603 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | License :: OSI Approved :: MIT LicenseOperating System :: OS IndependentProgramming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14 |
Evidence: shimmy-2.0.1-py3-none-any.whl
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