Architecture Overview

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Monorepo Structure

Flowise/
├── packages/
│   ├── server/          # Node.js backend
│   ├── ui/              # React frontend
│   ├── components/      # Node components
│   └── api-documentation/ # Swagger API docs
├── package.json         # Root workspace config
├── turbo.json          # Turbo build config
└── pnpm-workspace.yaml # PNPM workspace config

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Core Modules

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Server (packages/server)

• RESTful API endpoints
• Chatflow execution engine
• Database management (SQLite, MySQL, PostgreSQL)
• Authentication and authorization
• File storage and uploads
• WebSocket connections for streaming
• Credential management

• Framework: Express.js
• ORM: TypeORM
• Language: TypeScript
• Database: SQLite (default), MySQL, PostgreSQL

packages/server/
├── src/
│   ├── controllers/    # API route handlers
│   ├── services/       # Business logic
│   ├── database/       # Database entities & migrations
│   ├── utils/          # Helper functions
│   └── Interface.ts    # TypeScript interfaces
├── bin/               # Executable scripts
└── public/            # Static assets (icons, etc.)

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UI (packages/ui)

• Visual chatflow builder (drag-and-drop canvas)
• Node configuration forms
• Chatflow management (create, edit, delete)
• Chat interface for testing
• Settings and configuration UI
• Marketplace for community nodes

• Framework: React 18
• Build Tool: Vite
• UI Library: Material-UI (MUI)
• State Management: Redux Toolkit
• Canvas: React Flow
• Language: TypeScript

packages/ui/
├── src/
│   ├── ui-component/   # Reusable UI components
│   ├── views/          # Page components
│   ├── store/          # Redux store & slices
│   ├── api/            # API client functions
│   └── layout/         # Layout components
└── public/            # Static assets

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Components (packages/concepts/nodes-and-edges)

• LangChain component wrappers
• Custom tools and utilities
• Third-party API integrations
• Node definitions and metadata
• Credential schemas

• Language: TypeScript
• Core Library: LangChain
• Additional: Various third-party SDKs

packages/concepts/nodes-and-edges/
├── nodes/
│   ├── chatmodels/        # LLM integrations
│   ├── tools/             # Agent tools
│   ├── embeddings/        # Embedding models
│   ├── vectorstores/      # Vector databases
│   ├── documentloaders/   # Document loaders
│   ├── chains/            # LangChain chains
│   ├── agents/            # Agent implementations
│   ├── memory/            # Memory types
│   └── utilities/         # Helper nodes
├── credentials/          # Credential definitions
└── src/
    ├── Interface.ts      # Node interfaces
    └── utils.ts          # Utility functions

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API Documentation (packages/api-documentation)

• API documentation generation
• Interactive API explorer
• OpenAPI specification

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Data Flow

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Chatflow Creation

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Chatflow Execution

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Node System Architecture

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Node Lifecycle

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Node Structure

interface INode {
    // Metadata
    label: string           // Display name
    name: string           // Unique identifier
    version: number        // Version number
    description: string    // Description
    type: string          // Type identifier
    icon: string          // Icon filename
    category: string      // Category for grouping
    baseClasses: string[] // Supported base classes

    // Configuration
    inputs?: INodeParams[]        // Input parameters
    outputs?: INodeOutputsValue[] // Output definitions
    credential?: INodeParams      // Credential requirements

    // Methods
    init(nodeData: INodeData, input: string, options: ICommonObject): Promise<any>
    loadMethods?: { [key: string]: () => Promise<INodeOptionsValue[]> }
}

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Database Schema

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Key Entities

• Stores chatflow definitions
• Contains node configurations and connections
• Links to API keys and settings

• Stores conversation history
• Links to chatflows
• Contains user messages and AI responses

• Stores encrypted API keys and credentials
• Used by nodes requiring authentication

• Custom tools created by users
• Can be reused across chatflows

• OpenAI Assistant configurations
• Links to chatflows

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Build System

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Turbo Configuration

{
  "pipeline": {
    "build": {
      "dependsOn": ["^build"],
      "outputs": ["dist/**"]
    },
    "dev": {
      "cache": false,
      "persistent": true
    }
  }
}

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Build Order

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Package Management

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Workspace Structure

packages:
  - 'packages/*'
  - 'flowise'
  - 'ui'
  - 'components'
  - 'api-documentation'

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Key Scripts

pnpm install
# Installs all dependencies for all packages

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Technology Stack Summary

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Backend

• Runtime: Node.js >= 18.15.0
• Framework: Express.js
• ORM: TypeORM
• Database: SQLite, MySQL, PostgreSQL
• WebSocket: Socket.io
• Language: TypeScript

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Frontend

• Framework: React 18
• Build Tool: Vite
• UI Library: Material-UI (MUI)
• Canvas: React Flow
• State: Redux Toolkit
• Language: TypeScript

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AI/ML

• Core: LangChain
• Integrations: OpenAI, Anthropic, Google, and 100+ providers
• Vector Stores: Pinecone, Weaviate, Qdrant, and more

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DevOps

• Package Manager: PNPM v10
• Build System: Turbo
• Linting: ESLint
• Formatting: Prettier
• Git Hooks: Husky

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API Architecture

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RESTful Endpoints

• GET /api/v1/chatflows - List all chatflows
• POST /api/v1/chatflows - Create new chatflow
• GET /api/v1/chatflows/:id - Get chatflow details
• PUT /api/v1/chatflows/:id - Update chatflow
• DELETE /api/v1/chatflows/:id - Delete chatflow
• POST /api/v1/prediction/:id - Execute chatflow

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WebSocket Events

• start - Begin streaming
• token - Stream token
• end - End streaming
• error - Error occurred

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Security

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Credential Encryption

1. Secret key is generated on first run
2. Stored in SECRETKEY_PATH
3. Can be overridden with FLOWISE_SECRETKEY_OVERWRITE

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Environment Isolation

• TOOL_FUNCTION_BUILTIN_DEP - Allowed built-in modules
• TOOL_FUNCTION_EXTERNAL_DEP - Allowed external modules
• ALLOW_BUILTIN_DEP - Allow project dependencies

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Performance Considerations

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Caching

• Turbo caches build outputs
• LangChain supports cache backends
• Server caches node metadata

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Optimization

• Use streaming for large responses
• Lazy load components in UI
• Database connection pooling
• Static asset caching

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Extending Flowise

1. Custom Nodes - Add new components in packages/concepts/nodes-and-edges/nodes/
2. Custom Credentials - Define new credential types
3. Custom Tools - Create reusable tools in the UI
4. API Integration - Use Flowise API in external applications
5. Embedding - Embed chat widgets in websites

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Next Steps

• Set up local development
• Learn to create custom nodes
• Review contributing guidelines