llama.cpp/tools/server/webui

llama.cpp Web UI

A modern, feature-rich web interface for llama.cpp built with SvelteKit. This UI provides an intuitive chat interface with advanced file handling, conversation management, and comprehensive model interaction capabilities.

The WebUI supports two server operation modes:

• MODEL mode - Single model operation (standard llama-server)
• ROUTER mode - Multi-model operation with dynamic model loading/unloading

---

Table of Contents

• Features
• Getting Started
• Tech Stack
• Build Pipeline
• Architecture
• Data Flows
• Architectural Patterns
• Testing

---

Features

Chat Interface

• Streaming responses with real-time updates
• Reasoning content - Support for models with thinking/reasoning blocks
• Dark/light theme with system preference detection
• Responsive design for desktop and mobile

File Attachments

• Images - JPEG, PNG, GIF, WebP, SVG (with PNG conversion)
• Documents - PDF (text extraction or image conversion for vision models)
• Audio - MP3, WAV for audio-capable models
• Text files - Source code, markdown, and other text formats
• Drag-and-drop and paste support with rich previews

Conversation Management

• Branching - Branch messages conversations at any point by editing messages or regenerating responses, navigate between branches
• Regeneration - Regenerate responses with optional model switching (ROUTER mode)
• Import/Export - JSON format for backup and sharing
• Search - Find conversations by title or content

Advanced Rendering

• Syntax highlighting - Code blocks with language detection
• Math formulas - KaTeX rendering for LaTeX expressions
• Markdown - Full GFM support with tables, lists, and more

Multi-Model Support (ROUTER mode)

• Model selector with Loaded/Available groups
• Automatic loading - Models load on selection
• Modality validation - Prevents sending images to non-vision models
• LRU unloading - Server auto-manages model cache

Keyboard Shortcuts

Shortcut	Action
Shift+Ctrl/Cmd+O	New chat
Shift+Ctrl/Cmd+E	Edit conversation
Shift+Ctrl/Cmd+D	Delete conversation
Ctrl/Cmd+K	Search conversations
Ctrl/Cmd+B	Toggle sidebar

Developer Experience

• Request tracking - Monitor token generation with /slots endpoint
• Storybook - Component library with visual testing
• Hot reload - Instant updates during development

---

Getting Started

Prerequisites

• Node.js 18+ (20+ recommended)
• npm 9+
• llama-server running locally (for API access)

1. Install Dependencies

cd tools/server/webui
npm install

2. Start llama-server

In a separate terminal, start the backend server:

# Single model (MODEL mode)
./llama-server -m model.gguf

# Multi-model (ROUTER mode)
./llama-server --model-store /path/to/models

3. Start Development Servers

npm run dev

This starts:

• Vite dev server at http://localhost:5173 - The main WebUI
• Storybook at http://localhost:6006 - Component documentation

The Vite dev server proxies API requests to http://localhost:8080 (default llama-server port):

// vite.config.ts proxy configuration
proxy: {
  '/v1': 'http://localhost:8080',
  '/props': 'http://localhost:8080',
  '/slots': 'http://localhost:8080',
  '/models': 'http://localhost:8080'
}

Development Workflow

1. Open http://localhost:5173 in your browser
2. Make changes to .svelte, .ts, or .css files
3. Changes hot-reload instantly
4. Use Storybook at http://localhost:6006 for isolated component development

---

Tech Stack

Layer	Technology	Purpose
Framework	SvelteKit + Svelte 5	Reactive UI with runes ($state, $derived, $effect)
UI Components	shadcn-svelte + bits-ui	Accessible, customizable component library
Styling	TailwindCSS 4	Utility-first CSS with design tokens
Database	IndexedDB (Dexie)	Client-side storage for conversations and messages
Build	Vite	Fast bundling with static adapter
Testing	Playwright + Vitest + Storybook	E2E, unit, and visual testing
Markdown	remark + rehype	Markdown processing with KaTeX and syntax highlighting

Key Dependencies

{
	"svelte": "^5.0.0",
	"bits-ui": "^2.8.11",
	"dexie": "^4.0.11",
	"pdfjs-dist": "^5.4.54",
	"highlight.js": "^11.11.1",
	"rehype-katex": "^7.0.1"
}

---

Build Pipeline

Development Build

npm run dev

Runs Vite in development mode with:

• Hot Module Replacement (HMR)
• Source maps
• Proxy to llama-server

Production Build

npm run build

The build process:

1. Vite Build - Bundles all TypeScript, Svelte, and CSS
2. Static Adapter - Outputs to ../public (llama-server's static file directory)
3. Post-Build Script - Cleans up intermediate files
4. Custom Plugin - Creates index.html.gz with:
   • Inlined favicon as base64
   • GZIP compression (level 9)
   • Deterministic output (zeroed timestamps)

tools/server/webui/        →  build  →  tools/server/public/
├── src/                                 ├── index.html.gz  (served by llama-server)
├── static/                              └── (favicon inlined)
└── ...

SvelteKit Configuration

// svelte.config.js
adapter: adapter({
  pages: '../public',      // Output directory
  assets: '../public',     // Static assets
  fallback: 'index.html',  // SPA fallback
  strict: true
}),
output: {
  bundleStrategy: 'inline' // Single-file bundle
}

Integration with llama-server

The WebUI is embedded directly into the llama-server binary:

1. npm run build outputs index.html.gz to tools/server/public/
2. llama-server compiles this into the binary at build time
3. When accessing /, llama-server serves the gzipped HTML
4. All assets are inlined (CSS, JS, fonts, favicon)

This results in a single portable binary with the full WebUI included.

---

Architecture

The WebUI follows a layered architecture with unidirectional data flow:

Routes → Components → Hooks → Stores → Services → Storage/API

High-Level Architecture

See: docs/architecture/high-level-architecture-simplified.md

flowchart TB
    subgraph Routes["📍 Routes"]
        R1["/ (Welcome)"]
        R2["/chat/[id]"]
        RL["+layout.svelte"]
    end

    subgraph Components["🧩 Components"]
        C_Sidebar["ChatSidebar"]
        C_Screen["ChatScreen"]
        C_Form["ChatForm"]
        C_Messages["ChatMessages"]
        C_ModelsSelector["ModelsSelector"]
        C_Settings["ChatSettings"]
    end

    subgraph Stores["🗄️ Stores"]
        S1["chatStore"]
        S2["conversationsStore"]
        S3["modelsStore"]
        S4["serverStore"]
        S5["settingsStore"]
    end

    subgraph Services["⚙️ Services"]
        SV1["ChatService"]
        SV2["ModelsService"]
        SV3["PropsService"]
        SV4["DatabaseService"]
    end

    subgraph Storage["💾 Storage"]
        ST1["IndexedDB"]
        ST2["LocalStorage"]
    end

    subgraph APIs["🌐 llama-server"]
        API1["/v1/chat/completions"]
        API2["/props"]
        API3["/models/*"]
    end

    R1 & R2 --> C_Screen
    RL --> C_Sidebar
    C_Screen --> C_Form & C_Messages & C_Settings
    C_Screen --> S1 & S2
    C_ModelsSelector --> S3 & S4
    S1 --> SV1 & SV4
    S3 --> SV2 & SV3
    SV4 --> ST1
    SV1 --> API1
    SV2 --> API3
    SV3 --> API2

Layer Breakdown

Routes (src/routes/)

• / - Welcome screen, creates new conversation
• /chat/[id] - Active chat interface
• +layout.svelte - Sidebar, navigation, global initialization

Components (src/lib/components/)

Components are organized in app/ (application-specific) and ui/ (shadcn-svelte primitives).

Chat Components (app/chat/):

Component	Responsibility
ChatScreen/	Main chat container, coordinates message list, input form, and attachments
ChatForm/	Message input textarea with file upload, paste handling, keyboard shortcuts
ChatMessages/	Message list with branch navigation, regenerate/continue/edit actions
ChatAttachments/	File attachment previews, drag-and-drop, PDF/image/audio handling
ChatSettings/	Parameter sliders (temperature, top-p, etc.) with server default sync
ChatSidebar/	Conversation list, search, import/export, navigation

Dialog Components (app/dialogs/):

Component	Responsibility
DialogChatSettings	Full-screen settings configuration
DialogModelInformation	Model details (context size, modalities, parallel slots)
DialogChatAttachmentPreview	Full preview for images, PDFs (text or page view), code
DialogConfirmation	Generic confirmation for destructive actions
DialogConversationTitleUpdate	Edit conversation title

Server/Model Components (app/server/, app/models/):

Component	Responsibility
ServerErrorSplash	Error display when server is unreachable
ModelsSelector	Model dropdown with Loaded/Available groups (ROUTER mode)

Shared UI Components (app/misc/):

Component	Responsibility
MarkdownContent	Markdown rendering with KaTeX, syntax highlighting, copy buttons
SyntaxHighlightedCode	Code blocks with language detection and highlighting
ActionButton, ActionDropdown	Reusable action buttons and menus
BadgeModality, BadgeInfo	Status and capability badges

Hooks (src/lib/hooks/)

• useModelChangeValidation - Validates model switch against conversation modalities
• useProcessingState - Tracks streaming progress and token generation

Stores (src/lib/stores/)

Store	Responsibility
chatStore	Message sending, streaming, abort control, error handling
conversationsStore	CRUD for conversations, message branching, navigation
modelsStore	Model list, selection, loading/unloading (ROUTER)
serverStore	Server properties, role detection, modalities
settingsStore	User preferences, parameter sync with server defaults

Services (src/lib/services/)

Service	Responsibility
ChatService	API calls to/v1/chat/completions, SSE parsing
ModelsService	/models, /models/load, /models/unload
PropsService	/props, /props?model=
DatabaseService	IndexedDB operations via Dexie
ParameterSyncService	Syncs settings with server defaults

---

Data Flows

MODEL Mode (Single Model)

See: docs/flows/data-flow-simplified-model-mode.md

sequenceDiagram
    participant User
    participant UI
    participant Stores
    participant DB as IndexedDB
    participant API as llama-server

    Note over User,API: Initialization
    UI->>Stores: initialize()
    Stores->>DB: load conversations
    Stores->>API: GET /props
    API-->>Stores: server config
    Stores->>API: GET /v1/models
    API-->>Stores: single model (auto-selected)

    Note over User,API: Chat Flow
    User->>UI: send message
    Stores->>DB: save user message
    Stores->>API: POST /v1/chat/completions (stream)
    loop streaming
        API-->>Stores: SSE chunks
        Stores-->>UI: reactive update
    end
    Stores->>DB: save assistant message

ROUTER Mode (Multi-Model)

See: docs/flows/data-flow-simplified-router-mode.md

sequenceDiagram
    participant User
    participant UI
    participant Stores
    participant API as llama-server

    Note over User,API: Initialization
    Stores->>API: GET /props
    API-->>Stores: {role: "router"}
    Stores->>API: GET /models
    API-->>Stores: models[] with status

    Note over User,API: Model Selection
    User->>UI: select model
    alt model not loaded
        Stores->>API: POST /models/load
        loop poll status
            Stores->>API: GET /models
        end
        Stores->>API: GET /props?model=X
    end
    Stores->>Stores: validate modalities

    Note over User,API: Chat Flow
    Stores->>API: POST /v1/chat/completions {model: X}
    loop streaming
        API-->>Stores: SSE chunks + model info
    end

Detailed Flow Diagrams

Flow	Description	File
Chat	Message lifecycle, streaming, regeneration	chat-flow.md
Models	Loading, unloading, modality caching	models-flow.md
Server	Props fetching, role detection	server-flow.md
Conversations	CRUD, branching, import/export	conversations-flow.md
Database	IndexedDB schema, operations	database-flow.md
Settings	Parameter sync, user overrides	settings-flow.md

---

Architectural Patterns

1. Reactive State with Svelte 5 Runes

All stores use Svelte 5's fine-grained reactivity:

// Store with reactive state
class ChatStore {
	#isLoading = $state(false);
	#currentResponse = $state('');

	// Derived values auto-update
	get isStreaming() {
		return $derived(this.#isLoading && this.#currentResponse.length > 0);
	}
}

// Exported reactive accessors
export const isLoading = () => chatStore.isLoading;
export const currentResponse = () => chatStore.currentResponse;

2. Unidirectional Data Flow

Data flows in one direction, making state predictable:

flowchart LR
    subgraph UI["UI Layer"]
        A[User Action] --> B[Component]
    end

    subgraph State["State Layer"]
        B --> C[Store Method]
        C --> D[State Update]
    end

    subgraph IO["I/O Layer"]
        C --> E[Service]
        E --> F[API / IndexedDB]
        F -.->|Response| D
    end

    D -->|Reactive| B

Components dispatch actions to stores, stores coordinate with services for I/O, and state updates reactively propagate back to the UI.

3. Per-Conversation State

Enables concurrent streaming across multiple conversations:

class ChatStore {
	chatLoadingStates = new Map<string, boolean>();
	chatStreamingStates = new Map<string, { response: string; messageId: string }>();
	abortControllers = new Map<string, AbortController>();
}

4. Message Branching with Tree Structure

Conversations are stored as a tree, not a linear list:

interface DatabaseMessage {
	id: string;
	parent: string | null; // Points to parent message
	children: string[]; // List of child message IDs
	// ...
}

interface DatabaseConversation {
	currentNode: string; // Currently viewed branch tip
	// ...
}

Navigation between branches updates currentNode without losing history.

5. Layered Service Architecture

Stores handle state; services handle I/O:

┌─────────────────┐
│     Stores      │  Business logic, state management
├─────────────────┤
│    Services     │  API calls, database operations
├─────────────────┤
│   Storage/API   │  IndexedDB, LocalStorage, HTTP
└─────────────────┘

6. Server Role Abstraction

Single codebase handles both MODEL and ROUTER modes:

// serverStore.ts
get isRouterMode() {
  return this.role === ServerRole.ROUTER;
}

// Components conditionally render based on mode
{#if isRouterMode()}
  <ModelsSelector />
{/if}

7. Modality Validation

Prevents sending attachments to incompatible models:

// useModelChangeValidation hook
const validate = (modelId: string) => {
	const modelModalities = modelsStore.getModelModalities(modelId);
	const conversationModalities = conversationsStore.usedModalities;

	// Check if model supports all used modalities
	if (conversationModalities.hasImages && !modelModalities.vision) {
		return { valid: false, reason: 'Model does not support images' };
	}
	// ...
};

8. Persistent Storage Strategy

Data is persisted across sessions using two storage mechanisms:

flowchart TB
    subgraph Browser["Browser Storage"]
        subgraph IDB["IndexedDB (Dexie)"]
            C[Conversations]
            M[Messages]
        end
        subgraph LS["LocalStorage"]
            S[Settings Config]
            O[User Overrides]
            T[Theme Preference]
        end
    end

    subgraph Stores["Svelte Stores"]
        CS[conversationsStore] --> C
        CS --> M
        SS[settingsStore] --> S
        SS --> O
        SS --> T
    end

• IndexedDB: Conversations and messages (large, structured data)
• LocalStorage: Settings, user parameter overrides, theme (small key-value data)
• Memory only: Server props, model list (fetched fresh on each session)

---

Testing

Test Types

Type	Tool	Location	Command
E2E	Playwright	tests/e2e/	npm run test:e2e
Unit	Vitest	tests/client/, tests/server/	npm run test:unit
UI/Visual	Storybook + Vitest	tests/stories/	npm run test:ui

Running Tests

# All tests
npm run test

# Individual test suites
npm run test:e2e      # End-to-end (requires llama-server)
npm run test:client   # Client-side unit tests
npm run test:server   # Server-side unit tests
npm run test:ui       # Storybook visual tests

Storybook Development

npm run storybook     # Start Storybook dev server on :6006
npm run build-storybook  # Build static Storybook

Linting and Formatting

npm run lint          # Check code style
npm run format        # Auto-format with Prettier
npm run check         # TypeScript type checking

---

Project Structure

tools/server/webui/
├── src/
│   ├── lib/
│   │   ├── components/   # UI components (app/, ui/)
│   │   ├── hooks/        # Svelte hooks
│   │   ├── stores/       # State management
│   │   ├── services/     # API and database services
│   │   ├── types/        # TypeScript interfaces
│   │   └── utils/        # Utility functions
│   ├── routes/           # SvelteKit routes
│   └── styles/           # Global styles
├── static/               # Static assets
├── tests/                # Test files
├── docs/                 # Architecture diagrams
│   ├── architecture/     # High-level architecture
│   └── flows/            # Feature-specific flows
└── .storybook/           # Storybook configuration

---

Related Documentation

• llama.cpp Server README - Full server documentation
• Multimodal Documentation - Image and audio support
• Function Calling - Tool use capabilities