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conductor

JSONで定義したワークフローを自前のサーバーで動かし、障害のあとは止まったところから再開させるワークフローエンジン

公式Apache-2.0
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最終コミット
2026年8月28日

conductorとは

ワークフローをJSONで定義し、自分で立てたサーバーで実行するエンジンです。タスクごとに実行結果を保存するので、途中でサーバーが落ちても最初からやり直さず、止まったタスクから再開します。実際の処理はエンジンの外にいるワーカーが担当します。ワーカーは担当するタスクをHTTPでサーバーに問い合わせ、処理し、結果を返すだけの普通のプログラムなので、HTTPを呼べる言語ならどれでも書けます。公式SDKで実用段階にあるのはJava、Python、Go、JavaScript、C#で、RubyとRustはREADMEに試験段階と記されています。LLMの呼び出し、MCPサーバーからのツール取得、ベクトル検索は標準のタスク種別として用意されており、エージェントの繰り返し処理をフレームワークのコードなしで中断・再開できます。負担は運用面に出ます。JVM上で動かすサーバーであり、データベースと分散ロックを別に用意する必要があるうえ、OSS版には認証の仕組みがありません。

conductorで何ができますか?

  • ワークフローはJSONで書き、起動の入口は用途に合わせて選ぶ — 定義はタスクを並べたもので、各タスクに付けた参照名を通じて前のタスクの出力を読みます。実行を始める入口は、RESTまたはgRPCのAPI、Kafka・NATS・RabbitMQ・SQSに届いたイベント、内蔵のcronスケジューラから選べます。
  • ワーカーはHTTPで問い合わせるだけの普通のプログラム — 処理を書くコードはエンジンの外に置きます。担当するタスク種別をHTTPでサーバーに問い合わせ、処理し、成功か失敗かを返すだけなので、HTTPを呼べる言語ならどれでも書けます。エンジンがそのコードを再実行することはないため、時刻の取得も乱数も好きなライブラリも制約なく使えます。公式SDKで実用段階にあるのはJava、Python、Go、JavaScript、C#で、RubyとRustはREADMEに試験段階と記されています。
  • 落ちても続きから、人の承認は何週間でも待てる — タスクごとに結果が保存されるため、サーバーを再起動しても止まった位置から続きます。HUMANタスクを置くと、誰かがタスク更新APIで完了を伝えるまでワークフローは開いたまま待ち、待機用のタイマーや状態を自分で持つ必要はありません。
  • 分岐、繰り返し、並列化は組み込みの部品で書く — SWITCHで進む先を選び、DO_WHILEで条件が満たされるまで繰り返し、FORK_JOINで複数の枝を並行に走らせます。枝の数を実行中に決めたい場合はFORK_JOIN_DYNAMICを使い、後ろに置いたJOINが各枝の出力をまとめます。
  • LLM、MCPサーバー、ベクトル検索をワーカーなしで呼ぶ — LLM_CHAT_COMPLETEはAnthropic、OpenAI、Gemini、Bedrock、Ollamaなどに対応し、LIST_MCP_TOOLSとCALL_MCP_TOOLはHTTPで任意のMCPサーバーに接続し、登録と検索のタスクはPinecone、pgvector、MongoDB Atlasを扱えます。ただしプロバイダを使えるようにするのはサーバー側の作業で、APIキーを環境変数に設定してサーバーを再起動して初めて有効になり、そのあとはタスクのパラメータで切り替えられます。
  • 終わった実行を再生し、古い版はそのまま動かし続ける — 画面では各タスクの入力、出力、所要時間、再試行の履歴を追えます。最初からのやり直し、任意のタスクからの再実行、失敗した工程だけの再試行を選べるほか、定義には番号付きの版があり、走り始めた実行は最新版を明示して再開しない限り開始時の版のまま進みます。

conductorを選ぶ前に

  • OSS版のサーバー自体は呼び出し元を認証せず、RESTとgRPCのAPIも画面も到達できる人には開いているため、前段にプロキシが必要で、権限管理は商用版Orkesの機能です。
  • 取り込んで使うライブラリではなくJVM上で運用するサーバーで、公式の手引きが最も簡素とする本番構成でも、保存・キュー・検索を担うPostgreSQLと分散ロック用のRedisが要ります。

スター推移

8月17日〜8月28日 · +47

32.1k32.1k

よくある質問

conductorは商用利用できますか?

conductorはApache-2.0ライセンスで公開されています。OSI承認のオープンソースライセンスで、商用利用が認められています。

conductorはどの形で使えますか?

conductorはセルフホスト・マネージドクラウドの形で利用できます。

ドキュメント

conductor-oss/conductor のREADMEより転載(Apache-2.0)。 原文を読む ↗

Orchestrating distributed systems means wrestling with failures, retries, and state recovery. Conductor handles all of that so you don’t have to.

Conductor is an open-source, durable workflow engine built at Netflix for orchestrating microservices, AI agents, and durable workflows at internet scale. Trusted in production at Netflix, Tesla, LinkedIn, and J.P. Morgan. Actively maintained by Orkes and a growing community.

conductor_oss_getting_started


Get Running in 60 Seconds

Prerequisites: Node.js v16+ and Java 21+ must be installed.

npm install -g @conductor-oss/conductor-cli
conductor server start

Open http://localhost:8080 — your server is running with the built-in ui-next UI.

Upgrading from a previous version? The CLI caches the server JAR at ~/.conductor-cli/. If you have an older version cached, force a fresh download:

conductor server start latest
# or delete the cache manually
rm ~/.conductor-cli/conductor-server-latest.jar && conductor server start

Run your first workflow:

# Create a workflow that calls an API and parses the response — no workers needed
curl -s https://raw.githubusercontent.com/conductor-oss/conductor/main/docs/quickstart/workflow.json -o workflow.json
conductor workflow create workflow.json

Note: Running this command twice will return an error on the second call — the workflow already exists. This is expected behavior. Use conductor workflow update to modify an existing workflow.

conductor workflow start -w hello_workflow --sync

See the Quickstart guide for the full walkthrough, including writing workers and replaying workflows.

Docker Image for Conductor (includes the ui-next UI):

# UI at http://localhost:5000  |  API at http://localhost:8080
docker run -p 5000:5000 -p 8080:8080 conductoross/conductor:next

All CLI commands have equivalent cURL/API calls. See the Quickstart for details.


Why Conductor is the workflow engine of choice for developers

Durable executionEvery step is persisted. Survives crashes, restarts, and network failures with configurable retries and timeouts.
Deterministic by designOrchestration is separated from business logic — determinism is architectural, not developer discipline. Workers run any code; the workflow graph stays deterministic by construction.
AI agent orchestration14+ native LLM providers, MCP tool calling, function calling, human-in-the-loop approval, and vector databases for RAG.
Dynamic at runtimeDynamic forks, tasks, and sub-workflows resolved at runtime. LLMs generate JSON workflow definitions and Conductor executes them immediately.
Full replayabilityRestart from the beginning, rerun from any task, or retry just the failed step — on any workflow, at any time.
Internet scaleBattle-tested at Netflix, Tesla, LinkedIn, and J.P. Morgan. Scales horizontally to billions of workflow executions.
Polyglot workersWorkers in Java, Python, Go, JavaScript, C#, Ruby, or Rust. Workers poll, execute, and report — run them anywhere.
Self-hosted, no lock-inApache 2.0. 5 persistence backends, 6 message brokers. Runs anywhere Docker or a JVM runs.

Ship Agents, Not Framework Code

Conductor workers are plain code — any language, any library, any I/O. No determinism constraints, no SDK ritual. The orchestration layer is declarative and machine-readable, so LLMs generate and compose workflows natively. If an agent crashes at iteration 12, it resumes from iteration 12.

An autonomous think-act agent in Conductor: discover tools via MCP, reason with an LLM, call the chosen tool, repeat until done.

{
  "name": "autonomous_agent",
  "description": "Agent that loops until the task is complete",
  "version": 1,
  "tasks": [
    {
      "name": "discover_tools",
      "taskReferenceName": "discover",
      "type": "LIST_MCP_TOOLS",
      "inputParameters": {
        "mcpServer": "${workflow.input.mcpServerUrl}"
      }
    },
    {
      "name": "agent_loop",
      "taskReferenceName": "loop",
      "type": "DO_WHILE",
      "loopCondition": "if ($.loop['think'].output.result.done == true) { false; } else { true; }",
      "loopOver": [
        {
          "name": "think",
          "taskReferenceName": "think",
          "type": "LLM_CHAT_COMPLETE",
          "inputParameters": {
            "llmProvider": "openai",
            "model": "gpt-4o-mini",
            "messages": [
              {
                "role": "system",
                "message": "You are an autonomous agent. Available tools: ${discover.output.tools}. Previous results: ${loop.output.results}. Respond with JSON: {\"action\": \"tool_name\", \"arguments\": {}, \"done\": false} or {\"answer\": \"final answer\", \"done\": true}."
              },
              { "role": "user", "message": "${workflow.input.task}" }
            ]
          }
        },
        {
          "name": "act",
          "taskReferenceName": "act",
          "type": "SWITCH",
          "expression": "$.think.output.result.done ? 'done' : 'call_tool'",
          "decisionCases": {
            "call_tool": [
              {
                "name": "execute_tool",
                "taskReferenceName": "tool_call",
                "type": "CALL_MCP_TOOL",
                "inputParameters": {
                  "mcpServer": "${workflow.input.mcpServerUrl}",
                  "method": "${think.output.result.action}",
                  "arguments": "${think.output.result.arguments}"
                }
              }
            ]
          }
        }
      ]
    }
  ]
}

Every step is durably persisted — no framework, no SDK lock-in. Code-first engines force your code to be deterministic so the framework can replay it. Conductor makes the engine deterministic — so your code doesn’t have to be.

See the Build Your First AI Agent guide for the full walkthrough.


Conductor Skills for AI Coding Assistants

Conductor Skills let AI coding assistants (Claude Code, Gemini CLI, and others) create, manage, and deploy Conductor workflows directly from your terminal.

Claude

# Install Skills for Claude Code
/plugin marketplace add conductor-oss/conductor-skills
/plugin install conductor@conductor-skills

Install for all detected agents

One command to auto-detect every supported agent on your system and install globally where possible. Re-run anytime — it only installs for newly detected agents.

macOS / Linux

curl -sSL https://conductor-oss.github.io/conductor-skills/install.sh | bash -s -- --all

Windows (PowerShell) / (cmd)

# powershell
irm https://conductor-oss.github.io/conductor-skills/install.ps1 -OutFile install.ps1; .\install.ps1 -All

# cmd
powershell -c "irm https://conductor-oss.github.io/conductor-skills/install.ps1 -OutFile install.ps1; .\install.ps1 -All"

SDKs

LanguageRepositoryInstall
☕ Javaconductor-oss/java-sdkMaven Central
🐍 Pythonconductor-oss/python-sdkpip install conductor-python
🟨 JavaScriptconductor-oss/javascript-sdknpm install @io-orkes/conductor-javascript
🐹 Goconductor-oss/go-sdkgo get github.com/conductor-sdk/conductor-go
🟣 C#conductor-oss/csharp-sdkdotnet add package conductor-csharp
💎 Rubyconductor-oss/ruby-sdk(incubating)
🦀 Rustconductor-oss/rust-sdk(incubating)

Documentation & Community

  • Documentation — Architecture, guides, API reference, and cookbook recipes.
  • Slack — Community discussions and support.
  • Community Forum — Ask questions and share patterns.

BackendConfiguration
Redis + ES7 (default)config-redis.properties
Redis + ES8config-redis-es8.properties
Redis + OpenSearchconfig-redis-os.properties
Postgresconfig-postgres.properties
Postgres + ES7config-postgres-es7.properties
MySQL + ES7config-mysql.properties

Build From Source

Requirements: Docker Desktop, Java (JDK) 21+, Node.js 18+ and pnpm (for UI)

git clone https://github.com/conductor-oss/conductor
cd conductor
./gradlew build

# (optional) Build UI (ui-next) and embed it in the server
# ./build_ui_next.sh

# Start local server
cd server
../gradlew bootRun

Run the UI in dev mode (hot-reload at http://localhost:1234):

Requires a running Conductor server on http://localhost:8080. Enable corepack once if you haven’t already:

corepack enable

Then start the dev server:

cd ui-next
pnpm install
pnpm dev

Open http://localhost:1234 — the UI reloads automatically on file changes.

See the full build guide for details.


FAQ

Yes. Conductor OSS is the continuation of the original Netflix Conductor repository after Netflix contributed the project to the open-source foundation.

Yes. Conductor is a fully open-source workflow engine licensed under Apache 2.0. You can self-host on your own infrastructure with 5 persistence backends and 6 message brokers.

Yes. Orkes is the primary maintainer and offers an enterprise SaaS platform for Conductor across all major cloud providers.

Yes. Built at Netflix, battle-tested at internet scale. Conductor scales horizontally across multiple server instances to handle billions of workflow executions.

Yes. Conductor pioneered durable execution patterns, ensuring workflows and durable agents complete reliably despite infrastructure failures or crashes. Every step is persisted and recoverable.

Yes. Conductor preserves full execution history indefinitely. You can restart from the beginning, rerun from a specific task, or retry just the failed step — via API or UI.

Yes. Conductor provides native integration with 14+ LLM providers (Anthropic, OpenAI, Gemini, Bedrock, and more), MCP tool calling, function calling, human-in-the-loop approval, and vector database integration for RAG.

Coupling orchestration logic with business logic forces developers to maintain determinism constraints manually — no direct I/O, no system time, no randomness in workflow definitions. Conductor eliminates this entire class of bugs by making the orchestration layer deterministic by construction. Workers are plain code with zero framework constraints — write them in any language, use any library, call any API.

It depends on what you mean by “powerful.” In code-first engines, the workflow definition and your business logic live in the same runtime — which means the engine must replay your code to recover state. That forces determinism constraints on your business logic: no direct I/O, no system time, no threads, no randomness. Conductor separates these concerns. The orchestration graph is declarative (JSON), so it’s deterministic by construction. Your workers are plain code with zero constraints — use any language, any library, call any API. You get the full power of code where it matters (business logic) without the framework tax where it doesn’t (orchestration).

Yes. Conductor supports SWITCH (conditional branching), DO_WHILE (loops with configurable iteration cleanup), FORK_JOIN (parallel execution with dynamic fanout), SUB_WORKFLOW (composition), and DYNAMIC tasks resolved at runtime. These are composable — you can nest loops inside branches inside forks. For error handling, every task supports configurable retries, timeouts, and optional/compensating tasks. The declarative model doesn’t limit complexity — it makes complexity visible and debuggable.

Workflow definitions are versioned by number. Running executions continue on the version they started with — deploying a new version never breaks in-flight workflows. There’s no replay compatibility problem because Conductor doesn’t replay your code. The orchestration graph is the source of truth, and each execution is pinned to its definition version. Update orchestration logic without redeploying workers and without worrying about breaking running workflows.

Conductor provides a built-in visual UI for designing, running, and debugging workflows. Every execution is fully observable: you can inspect the input, output, timing, and retry history of every task. For type safety, Conductor validates workflow inputs and task I/O against JSON Schema. Workers are plain code in your language of choice — you get full IDE support, type checking, and debugging for your business logic. The orchestration layer is visible in the UI, not hidden inside a framework.

Yes. Conductor is designed for long-running workflows. Executions are fully persisted — a workflow can pause for months waiting for a human approval, an external signal, or a scheduled timer, and resume exactly where it left off. There’s no in-memory state to lose. This is the same mechanism that makes AI agent loops durable: if iteration 12 waits for a human review for three weeks, iteration 13 picks up right where it left off.

You gain flexibility. Because workflows are JSON, LLMs can generate and modify them at runtime — no compile/deploy cycle. Dynamic forks let you fan out to a variable number of parallel tasks determined at runtime. Dynamic sub-workflows let one workflow compose others by name. And because workers are decoupled from orchestration, you can update the workflow graph or swap worker implementations independently. Code-first engines couple these together, so changing orchestration means redeploying and re-versioning your code.

Conductor is an open-source workflow engine with native LLM task types for 14+ providers, built-in MCP integration, durable execution, full replayability, and 7 language SDKs. Unlike code-first engines, Conductor separates orchestration from business logic — determinism is an architectural guarantee, not a developer constraint. Your workers are plain code with zero framework rules. The orchestration layer is declarative, so it’s observable, versionable, and composable by LLMs. Battle-tested at Netflix, Tesla, LinkedIn, and J.P. Morgan.

100% compatible. Orkes Conductor is built on top of Conductor OSS with full API and workflow compatibility.


Roadmap

See the Conductor OSS Roadmap. Want to participate? Reach out.

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