---
id: shimmy
version: "2.0.1"
license: unclear
license_treatment: permissive
maintenance: active
---

# Shimmy — An API conversion tool providing Gymnasium and PettingZoo bindings for popular external reinforcement learning environments.

License: permissive · Maintenance: active · Downloads: 251.0K/mo

## 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 above — verify before relying.

Shimmy converts external reinforcement learning environments to Gymnasium and PettingZoo APIs, letting you use popular RL simulators with a unified interface.

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

pip install shimmy
uv add shimmy
poetry add shimmy

## Installing Shimmy

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.

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 APIs

Requires Python 3.10 or later; numpy and gymnasium must be installed as runtime dependencies.

Verify 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: not declared (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: active
- Downloads: 251.0K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

reinforcement learning environment adapter, gymnasium bindings, pettingzoo api wrapper, rl environment converter, external gym environment bridge, multi-environment rl interface, reinforcement-learning, environment-adapter, api-wrapper

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