gymnasium

https://github.com/Farama-Foundation/PettingZoo An API standard for multi-agent reinforcement learning environments, with popular reference environments and related utilities

https://github.com/Farama-Foundation/Gymnasium An API standard for single-agent reinforcement learning environments, with popular reference environments and related utilities (formerly Gym)

https://github.com/Farama-Foundation/Minigrid Simple and easily configurable grid world environments for reinforcement learning

https://github.com/Farama-Foundation/Minari A standard format for offline reinforcement learning datasets, with popular reference datasets and related utilities