Atmosphere

A JVM framework by JetBrains for building predictable, fault-tolerant, enterprise-ready AI agents across all platforms — from backend services to Android, iOS, and in-browser environments, with built-in MCP and multi-provider LLM support.

Ouroboros is a spec-driven multi-agent framework that shifts from traditional prompting to specification-driven development, supporting multi-agent collaboration, MCP tool integration, and automated workflow orchestration for building high-quality agent systems.

AG2 (formerly AutoGen) is an open-source AgentOS providing a multi-agent conversation framework with flexible agent orchestration, tool integration, and distributed collaboration for building complex multi-agent systems.

Agent-oriented programming framework for building LLM applications in Java. Provides agent abstractions, tool calling, multi-agent collaboration, and other core capabilities for enterprise Java ecosystem integration.