Overview

ElizaOS is built with a modular, extensible architecture that supports agent-based computing, plugin extensibility, and real-time communication. The system is designed around a core runtime that manages agent lifecycle, memory, and execution while providing a flexible plugin system for customization.

System Architecture

Core Runtime (@elizaos/core)

The heart of ElizaOS is the AgentRuntime class, which provides:

• Agent Lifecycle Management: Initialization, execution, and cleanup of agent instances
• Memory Management: Persistent storage and retrieval of conversation history, facts, and knowledge
• State Composition: Dynamic state building from multiple providers and data sources
• Action Processing: Execution of agent actions and response generation
• Plugin Integration: Loading and management of plugins that extend agent capabilities
• Event System: Internal event bus for decoupled communication between components

Client-Server Architecture

ElizaOS uses a distributed architecture with clear separation between client and server:

Server Components (@elizaos/server):

• HTTP API: Express.js-based REST endpoints for agent management and system operations
• WebSocket Server: Real-time communication using Socket.IO for live chat and notifications
• Agent Management: Multi-agent support with isolated runtime environments
• Upload Handling: File and media processing capabilities
• Authentication: Middleware for secure access control

Client Components (@elizaos/client):

• React Application: Modern web interface built with React 19 and TypeScript
• Real-time Chat: WebSocket-based chat interface with message streaming
• Agent Management: UI for creating, configuring, and monitoring agents
• Memory Visualization: Interactive views of agent memory and knowledge graphs
• Plugin Configuration: Interface for managing plugin settings and integrations

Plugin System

The plugin architecture enables extensibility through standardized interfaces:

Plugin Structure:

interface Plugin {
  name: string;
  description: string;
  actions?: Action[];
  evaluators?: Evaluator[];
  providers?: Provider[];
  services?: Service[];
}

Core Plugin Types:

• Actions: Executable behaviors that agents can perform
• Evaluators: Decision-making components for response evaluation
• Providers: Data and service integration adapters
• Services: System-level utilities and background processes

Project Structure

The ElizaOS monorepo is organized into focused packages:

packages/
├── core/                 # Core runtime and types (@elizaos/core)
├── cli/                  # Command-line interface (@elizaos/cli)
├── client/              # Web client application (@elizaos/client)
├── server/              # HTTP/WebSocket server (@elizaos/server)
├── api-client/          # API client library (@elizaos/api-client)
├── plugin-*/            # Individual plugin packages
└── create-eliza/        # Project bootstrapping tool

Package Organization

Core Package (@elizaos/core):

• runtime.ts: AgentRuntime class and core execution logic
• types/: TypeScript type definitions for all system components
• database.ts: Database adapter interfaces and implementations
• actions.ts: Action composition and execution utilities
• entities.ts: Entity resolution and relationship management
• prompts.ts: Prompt templates and context injection
• services.ts: Service registry and lifecycle management

CLI Package (@elizaos/cli):

• Command implementations for project management
• Template system for project and plugin creation
• Development server with hot reloading
• Testing framework integration
• Build and deployment utilities

Client Package (@elizaos/client):

• React components for agent interaction
• Real-time communication hooks
• State management with React Context
• Plugin configuration interfaces
• Memory and knowledge visualization

Server Package (@elizaos/server):

• Express.js server with middleware
• WebSocket handlers for real-time communication
• Multi-agent runtime management
• File upload and media processing
• Authentication and authorization

Design Principles

Modularity and Separation of Concerns

• Clear Boundaries: Each package has well-defined responsibilities
• Interface-Driven: Components communicate through typed interfaces
• Dependency Injection: Services and providers are injected rather than tightly coupled
• Plugin Isolation: Plugins operate in isolated environments with controlled access

Extensibility and Plugin Architecture

• Standardized Interfaces: All plugins implement consistent interfaces
• Runtime Loading: Plugins can be loaded and unloaded at runtime
• Configuration Management: Plugin settings are managed through environment variables
• Dependency Resolution: Automatic resolution of plugin dependencies

Performance and Scalability

• Memory Management: Efficient memory usage with configurable limits
• Asynchronous Processing: Non-blocking operations throughout the system
• Connection Pooling: Database connections are pooled for efficiency
• Caching: Intelligent caching of frequently accessed data

Security and Reliability

• Input Validation: All user inputs are validated and sanitized
• Environment Isolation: Sensitive configuration is isolated from application code
• Error Handling: Comprehensive error handling with graceful degradation
• Audit Logging: Detailed logging for security and debugging

Runtime Architecture

Agent Execution Flow

1. Initialization: Agent runtime loads character definition and plugins
2. State Composition: Dynamic state is built from providers and memory
3. Message Processing: Incoming messages are analyzed and actions are selected
4. Action Execution: Selected actions are executed with proper context
5. Response Generation: AI models generate responses based on character and context
6. Memory Storage: Conversation history and facts are persisted to memory

Memory and State Management

• Vector Embeddings: Semantic search capabilities for memory retrieval
• Entity Resolution: Intelligent entity identification and relationship tracking
• Context Windows: Efficient context management for large conversations
• Knowledge Graph: Structured knowledge representation with relationships

Communication Patterns

• Event-Driven: Components communicate through events rather than direct calls
• Message Bus: Internal pub/sub system for decoupled communication
• Real-time Updates: WebSocket connections for instant UI updates
• API Consistency: Unified API patterns across all endpoints

Development Workflow

Local Development

1. Project Creation: Use elizaos create to bootstrap new projects
2. Development Server: Run elizaos dev for hot reloading development
3. Testing: Comprehensive test suite with elizaos test
4. Plugin Development: Create and test plugins in isolation

Production Deployment

• Build System: TypeScript compilation with optimized output
• Container Support: Docker containerization for consistent deployment
• Environment Management: Hierarchical configuration with secret management
• Monitoring: Built-in health checks and performance metrics

This architecture provides a solid foundation for building sophisticated AI agents while maintaining flexibility, performance, and reliability.