eino

eino

The ultimate LLM/AI application development framework in Go.

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Eino is an ultimate LLM application development framework in Golang, emphasizing simplicity, scalability, reliability, and effectiveness. It provides a curated list of component abstractions, a powerful composition framework, meticulously designed APIs, best practices, and tools covering the entire development cycle. Eino standardizes and improves efficiency in AI application development by offering rich components, powerful orchestration, complete stream processing, highly extensible aspects, and a comprehensive framework structure.

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Eino

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Overview

Eino['aino] is an LLM application development framework in Golang. It draws from LangChain, Google ADK, and other open-source frameworks, and is designed to follow Golang conventions.

Eino provides:

  • Components: reusable building blocks like ChatModel, Tool, Retriever, and ChatTemplate, with official implementations for OpenAI, Ollama, and more.
  • Agent Development Kit (ADK): build AI agents with tool use, multi-agent coordination, context management, interrupt/resume for human-in-the-loop, and ready-to-use agent patterns.
  • Composition: connect components into graphs and workflows that can run standalone or be exposed as tools for agents.
  • Examples: working code for common patterns and real-world use cases.

Quick Start

ChatModelAgent

Configure a ChatModel, optionally add tools, and you have a working agent:

chatModel, _ := openai.NewChatModel(ctx, &openai.ChatModelConfig{
    Model:  "gpt-4o",
    APIKey: os.Getenv("OPENAI_API_KEY"),
})

agent, _ := adk.NewChatModelAgent(ctx, &adk.ChatModelAgentConfig{
    Model: chatModel,
})

runner := adk.NewRunner(ctx, adk.RunnerConfig{Agent: agent})
iter := runner.Query(ctx, "Hello, who are you?")
for {
    event, ok := iter.Next()
    if !ok {
        break
    }
    fmt.Println(event.Message.Content)
}

Add tools to give the agent capabilities:

agent, _ := adk.NewChatModelAgent(ctx, &adk.ChatModelAgentConfig{
    Model: chatModel,
    ToolsConfig: adk.ToolsConfig{
        ToolsNodeConfig: compose.ToolsNodeConfig{
            Tools: []tool.BaseTool{weatherTool, calculatorTool},
        },
    },
})

The agent handles the ReAct loop internally — it decides when to call tools and when to respond.

ChatModelAgent examples · docs

DeepAgent

For complex tasks, use DeepAgent. It breaks down problems into steps, delegates to sub-agents, and tracks progress:

deepAgent, _ := deep.New(ctx, &deep.Config{
    ChatModel: chatModel,
    SubAgents: []adk.Agent{researchAgent, codeAgent},
    ToolsConfig: adk.ToolsConfig{
        ToolsNodeConfig: compose.ToolsNodeConfig{
            Tools: []tool.BaseTool{shellTool, pythonTool, webSearchTool},
        },
    },
})

runner := adk.NewRunner(ctx, adk.RunnerConfig{Agent: deepAgent})
iter := runner.Query(ctx, "Analyze the sales data in report.csv and generate a summary chart")

DeepAgent can be configured to coordinate multiple specialized agents, run shell commands, execute Python code, and search the web.

DeepAgent example · docs

Composition

When you need precise control over execution flow, use compose to build graphs and workflows:

graph := compose.NewGraph[*Input, *Output]()
graph.AddLambdaNode("validate", validateFn)
graph.AddChatModelNode("generate", chatModel)
graph.AddLambdaNode("format", formatFn)

graph.AddEdge(compose.START, "validate")
graph.AddEdge("validate", "generate")
graph.AddEdge("generate", "format")
graph.AddEdge("format", compose.END)

runnable, _ := graph.Compile(ctx)
result, _ := runnable.Invoke(ctx, input)

Compositions can be exposed as tools for agents, bridging deterministic workflows with autonomous behavior:

tool, _ := graphtool.NewInvokableGraphTool(graph, "data_pipeline", "Process and validate data")

agent, _ := adk.NewChatModelAgent(ctx, &adk.ChatModelAgentConfig{
    Model: chatModel,
    ToolsConfig: adk.ToolsConfig{
        ToolsNodeConfig: compose.ToolsNodeConfig{
            Tools: []tool.BaseTool{tool},
        },
    },
})

This lets you build domain-specific pipelines with exact control, then let agents decide when to use them.

GraphTool examples · compose docs

Key Features

Component Ecosystem

Eino defines component abstractions (ChatModel, Tool, Retriever, Embedding, etc.) with official implementations for OpenAI, Claude, Gemini, Ark, Ollama, Elasticsearch, and more.

eino-ext

Stream Processing

Eino automatically handles streaming throughout orchestration: concatenating, boxing, merging, and copying streams as data flows between nodes. Components only implement the streaming paradigms that make sense for them; the framework handles the rest.

docs

Callback Aspects

Inject logging, tracing, and metrics at fixed points (OnStart, OnEnd, OnError, OnStartWithStreamInput, OnEndWithStreamOutput) across components, graphs, and agents.

docs

Interrupt/Resume

Any agent or tool can pause execution for human input and resume from checkpoint. The framework handles state persistence and routing.

docs · examples

Framework Structure

The Eino framework consists of:

  • Eino (this repo): Type definitions, streaming mechanism, component abstractions, orchestration, agent implementations, aspect mechanisms

  • EinoExt: Component implementations, callback handlers, usage examples, evaluators, prompt optimizers

  • Eino Devops: Visualized development and debugging

  • EinoExamples: Example applications and best practices

Documentation

Dependencies

  • Go 1.18 and above.

Code Style

This repo uses golangci-lint. Check locally with:

golangci-lint run ./...

Rules enforced:

  • Exported functions, interfaces, packages, etc. should have GoDoc comments
  • Code should be formatted with gofmt -s
  • Import order should follow goimports (std -> third party -> local)

Security

If you discover a potential security issue, notify Bytedance Security via the security center or vulnerability reporting email.

Do not create a public GitHub issue.

Contact

    LarkGroup

License

This project is licensed under the Apache-2.0 License.

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