A popular open-source framework for multi-agent systems, where several agents with distinct roles collaborate on a job. CrewAI is known for a cleaner, more approachable design than the older frameworks, which makes standing up a small crew of cooperating agents quicker for developers.
Like LangChain it is code aimed at engineers, not a finished app, and multi-agent setups add their own complexity and cost to debug. For developers specifically building agents that work as a team, it is one of the most-liked options.