@memberjunction/ai-local-embeddings

MemberJunction AI provider for local text embeddings using Transformers.js. This package runs embedding models directly on your machine, eliminating the need for external API calls, API keys, or per-token charges.

Architecture

graph TD
    A["LocalEmbedding<br/>(Provider)"] -->|extends| B["BaseEmbeddings<br/>(@memberjunction/ai)"]
    A -->|uses| C["Transformers.js<br/>(@xenova/transformers)"]
    C -->|loads from| D["Hugging Face Hub<br/>(or local cache)"]
    C -->|runs| E["Feature Extraction<br/>Pipeline"]
    E -->|generates| F["Embedding Vectors"]
    B -->|registered via| G["@RegisterClass"]

    style A fill:#7c5295,stroke:#563a6b,color:#fff
    style B fill:#2d6a9f,stroke:#1a4971,color:#fff
    style C fill:#2d8659,stroke:#1a5c3a,color:#fff
    style D fill:#b8762f,stroke:#8a5722,color:#fff
    style E fill:#2d6a9f,stroke:#1a4971,color:#fff
    style F fill:#2d8659,stroke:#1a5c3a,color:#fff
    style G fill:#b8762f,stroke:#8a5722,color:#fff

Features

• Offline Operation: Run embedding models locally without internet (after initial download)
• No API Keys Required: Eliminate dependency on external services
• Cost-Effective: No per-token charges for embeddings
• Privacy-Focused: Data never leaves your infrastructure
• Multiple Models: Support for various sentence-transformer models from Hugging Face
• Automatic Caching: Models are downloaded once and cached locally
• Batch Processing: Efficient batch embedding with configurable batch sizes (default 32)
• Model Preloading: Warm up models before first inference
• Quantized Models: Use quantized models for better performance

Supported Models

Model	Dimensions	Description
all-MiniLM-L6-v2	384	Lightweight general-purpose embeddings
all-MiniLM-L12-v2	384	Higher quality with more layers
all-mpnet-base-v2	768	Best quality general-purpose embeddings
paraphrase-multilingual-MiniLM-L12-v2	384	Multilingual support (50+ languages)
gte-small	384	General Text Embeddings (efficient)
bge-small-en-v1.5	384	BAAI General Embeddings (English)

Installation

npm install @memberjunction/ai-local-embeddings

Usage

Single Text Embedding

import { LocalEmbedding } from '@memberjunction/ai-local-embeddings';

const embedder = new LocalEmbedding();

const result = await embedder.EmbedText({
    text: 'Your text to embed',
    model: 'Xenova/all-MiniLM-L6-v2'
});

console.log(result.vector); // Float32Array of embedding values

Batch Embedding

const results = await embedder.EmbedTexts({
    texts: ['First text', 'Second text', 'Third text'],
    model: 'Xenova/all-MiniLM-L6-v2'
});

console.log(results.vectors.length); // 3 embedding vectors

Configuration

embedder.SetAdditionalSettings({
    cacheDir: '/path/to/model/cache',
    useQuantized: true
});

Model Management

// Preload a model for faster first inference
await embedder.preloadModel('Xenova/all-mpnet-base-v2');

// Clear model cache to free memory
embedder.clearCache();
LocalEmbedding.clearSharedCache(); // Static method

Environment Variables

Variable	Default	Description
TRANSFORMERS_CACHE_DIR	./.cache/transformers	Directory for storing downloaded models
TRANSFORMERS_LOCAL_URL	(empty)	Optional local URL for model files

ESM/CommonJS Compatibility

This package is built as CommonJS. The underlying @xenova/transformers library is ESM-only, so dynamic imports are used as a workaround (the official recommended approach by HuggingFace for CommonJS environments).

Class Registration

Registered as LocalEmbedding via @RegisterClass(BaseEmbeddings, 'LocalEmbedding').

Dependencies

• @memberjunction/ai - Core AI abstractions
• @memberjunction/global - Class registration
• @xenova/transformers - Hugging Face Transformers.js runtime