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Koog

Kotlin-native AI agent framework by JetBrains with MCP support

Koog is JetBrains official Kotlin-native framework for building predictable, fault-tolerant AI agents. It provides structured agent workflows with MCP protocol support, type-safe tool definitions, and deterministic execution patterns designed for JVM production environments. As the first production-grade Kotlin agent framework, it fills the gap in a JVM ecosystem dominated by Python-based alternatives and integrates naturally with existing Kotlin and Java backend infrastructure.

About Koog

Koog brings AI agent development to the Kotlin ecosystem with a framework that emphasizes predictability and fault tolerance over the flexible but sometimes unpredictable patterns common in Python agent libraries. Agent workflows are defined using Kotlin DSL constructs with type-safe tool definitions, structured output parsing, and deterministic execution paths that make agent behavior easier to test and debug. The framework integrates with the Model Context Protocol for standardized tool integration across different LLM providers.

The architecture targets JVM production environments where teams already operate Kotlin or Java backend services. Rather than requiring a separate Python runtime for agent logic, Koog lets teams build agents using the same language, build tools, and deployment pipelines as their existing backend infrastructure. Coroutine-based concurrency handles parallel tool execution efficiently, and the structured error handling patterns provide clear recovery paths when individual tool calls fail during complex agent workflows.

Developed as an official JetBrains project, Koog benefits from the engineering rigor and long-term support commitment that characterize JetBrains open-source efforts. With over 3,600 GitHub stars and rapid growth following its announcement at KotlinConf, the framework is gaining traction among teams that want agent capabilities without adding Python to their technology stack. The Apache 2.0 license enables commercial use, and JetBrains internal usage provides real-world validation of the framework reliability and performance characteristics.

Pricing & Platform Specs

Pricing Summary

100% free and open-source under the Apache-2.0 license developed by JetBrains. Koog has zero licensing fees; developers only pay for their chosen LLM provider API usage (OpenAI, Anthropic, Gemini) and JVM infrastructure compute.

full pricing breakdown →

Supported Platforms

JVM (Kotlin/Java) on any platform

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Alternatives

All Koog alternatives →

Open-source general AI agent framework from the MetaGPT team

OpenManus is an open-source framework for building general-purpose AI agents, developed by core contributors from the MetaGPT community. It provides a modular architecture with planning agents, reactive agents, and tool-calling agents that can execute code, browse the web, search for information, and handle files. Built as the open alternative to Manus AI, it gained over 55,000 GitHub stars and supports multi-agent collaboration with real-time execution feedback.

Open Source

Transparent AI agent framework with 100+ skills and real-time visibility

Agent Zero is an open-source general-purpose AI agent framework with 16,700+ GitHub stars that uses the computer itself as a tool. Unlike structured orchestration frameworks, it provides full transparency where every thought, action, and tool call is visible and editable in real time, supporting 100+ extensible skills.

Open Source

Behavioral control layer for reliable customer-facing AI agents

Parlant is an open-source framework that adds behavioral governance to conversational AI agents. Instead of relying on prompt engineering alone, it lets teams define explicit policies, conversation guidelines, and behavioral rules that agents follow predictably across multi-turn interactions. Parlant sits between the LLM and the user-facing interface, enforcing consistent agent behavior for customer support, sales, and service automation use cases.

Open Source

Community experience

Sources & verification

Sources checked
Content verified

Verification dates are editorial checks. Routine CMS saves and automatic updatedAt timestamps do not advance them.

FAQ

What is Koog?

Koog is JetBrains official Kotlin-native framework for building predictable, fault-tolerant AI agents. It provides structured agent workflows with MCP protocol support, type-safe tool definitions, and deterministic execution patterns designed for JVM production environments. As the first production-grade Kotlin agent framework, it fills the gap in a JVM ecosystem dominated by Python-based alternatives and integrates naturally with existing Kotlin and Java backend infrastructure.

Is Koog free?

Yes — Koog is open source and free to use. 100% free and open-source under the Apache-2.0 license developed by JetBrains. Koog has zero licensing fees; developers only pay for their chosen LLM provider API usage (OpenAI, Anthropic, Gemini) and JVM infrastructure compute.

Is Koog open source?

Yes — Koog is open source.

Is Koog still maintained?

Yes — Koog is active. Its listing was last verified on September 6, 2026.

What are the best Koog alternatives?

The first editor-selected Koog alternatives are OpenManus, Agent Zero, Parlant.