ChatArena is an open-source Python framework maintained by the Farama Foundation that provides multi-agent language game environments for large language models. Its primary goal is to facilitate research into the communication, collaboration, and competition (C3) capabilities of LLM-based agents by placing them in structured game settings. The library is built around three core abstractions: an Arena (which manages the game loop and UI), Environments (which encode game state and rules, rendering observations in natural language), and Language Backends (which supply the language intelligence by accepting text input and returning text responses). This modular design lets researchers swap in different LLMs or define entirely new game environments without rewriting the surrounding infrastructure. ChatArena ships with several built-in game environments including a general conversational multi-player arena, an NLP Classroom simulation, Rock-Paper-Scissors with a moderator, Tic-Tac-Toe, and a social-deduction Chameleon game. The framework supports multiple LLM backends including OpenAI, Anthropic, Cohere, and HuggingFace, installable via extras (e.g., pip install chatarena[all_backends]). Both a Web UI and a CLI are provided for prompt engineering and observing agent interactions. As of August 11, 2025, the Farama Foundation officially deprecated ChatArena due to a lack of widespread community adoption, stating it will receive no further updates or support. The repository and PyPI package (latest version 0.1.18) remain publicly accessible under the Apache License, but the project is no longer under active development. Key features: - Modular Arena/Environment/Backend architecture for composable multi-agent game setups - Built-in environments: conversational arena, NLP Classroom, Rock-Paper-Scissors, Tic-Tac-Toe, Chameleon (social deduction) - Support for multiple LLM backends: OpenAI, Anthropic, Cohere, HuggingFace - Web UI and CLI interfaces for interactive agent development and prompt engineering - PettingZoo-compatible environment abstraction for RL library integration - Published on PyPI (pip install chatarena); Apache License open-source - Officially deprecated by Farama Foundation in August 2025 — no further updates planned
Free and open-source (Apache License). No paid tiers. Users pay only for any external LLM API usage (e.g., OpenAI, Anthropic).