Moondream Node.js Client Library

Official Node.js client library for Moondream, a fast multi-function VLM. This client can target either Moondream Cloud or Moondream Station.

Capabilities

Moondream goes beyond the typical VLM "query" ability to include more visual functions:

Method	Description
caption	Generate descriptive captions for images
query	Ask questions about image content
detect	Find bounding boxes around objects in images
point	Identify the center location of specified objects
segment	Generate an SVG path segmentation mask for objects

Try it out on Moondream's playground.

Installation

npm install moondream

Quick Start

Choose how you want to run Moondream:

1. Moondream Cloud — Get an API key from the cloud console
2. Moondream Station — Run locally by installing Moondream Station

import { vl } from 'moondream';
import fs from 'fs';

// Initialize with Moondream Cloud
const model = new vl({ apiKey: '<your-api-key>' });

// Or initialize with a local Moondream Station
const model = new vl({ endpoint: 'http://localhost:2020/v1' });

// Load an image
const image = fs.readFileSync('path/to/image.jpg');

// Generate a caption
const caption = await model.caption({ image });
console.log('Caption:', caption.caption);

// Ask a question
const answer = await model.query({ image, question: "What's in this image?" });
console.log('Answer:', answer.answer);

// Stream the response
const stream = await model.caption({ image, stream: true });
for await (const chunk of stream.caption) {
  process.stdout.write(chunk);
}

API Reference

Constructor

const model = new vl({ apiKey: '<your-api-key>' });           // Cloud
const model = new vl({ endpoint: 'http://localhost:2020/v1' }); // Local

Methods

caption({ image, length?, stream? })

Generate a caption for an image.

Parameters:

• image — Buffer or Base64EncodedImage
• length — "normal", "short", or "long" (default: "normal")
• stream — boolean (default: false)

Returns: CaptionOutput — { caption: string | AsyncGenerator }

const result = await model.caption({ image, length: 'short' });
console.log(result.caption);

// With streaming
const stream = await model.caption({ image, stream: true });
for await (const chunk of stream.caption) {
  process.stdout.write(chunk);
}

---

query({ image?, question, stream? })

Ask a question about an image.

Parameters:

• image — Buffer or Base64EncodedImage (optional)
• question — string
• stream — boolean (default: false)

Returns: QueryOutput — { answer: string | AsyncGenerator }

const result = await model.query({ image, question: "What's in this image?" });
console.log(result.answer);

// With streaming
const stream = await model.query({ image, question: "Describe this", stream: true });
for await (const chunk of stream.answer) {
  process.stdout.write(chunk);
}

---

detect({ image, object })

Detect specific objects in an image.

Parameters:

• image — Buffer or Base64EncodedImage
• object — string

Returns: DetectOutput — { objects: DetectedObject[] }

const result = await model.detect({ image, object: 'car' });
console.log(result.objects);

---

point({ image, object })

Get coordinates of specific objects in an image.

Parameters:

• image — Buffer or Base64EncodedImage
• object — string

Returns: PointOutput — { points: Point[] }

const result = await model.point({ image, object: 'person' });
console.log(result.points);

---

segment({ image, object, spatialRefs?, stream? })

Segment an object from an image and return an SVG path.

Parameters:

• image — Buffer or Base64EncodedImage
• object — string
• spatialRefs — Array<[x, y] | [x1, y1, x2, y2]> — optional spatial hints (normalized 0-1)
• stream — boolean (default: false)

Returns:

• Non-streaming: SegmentOutput — { path: string, bbox?: SegmentBbox }
• Streaming: SegmentStreamOutput — { stream: AsyncGenerator<SegmentStreamChunk> }

const result = await model.segment({ image, object: 'cat' });
console.log(result.path);  // SVG path string
console.log(result.bbox);  // { x_min, y_min, x_max, y_max }

// With spatial hint (point)
const result = await model.segment({ image, object: 'cat', spatialRefs: [[0.5, 0.5]] });

// With streaming
const stream = await model.segment({ image, object: 'cat', stream: true });
for await (const update of stream.stream) {
  if (update.bbox && !update.completed) {
    console.log('Bbox:', update.bbox);  // Available immediately
  }
  if (update.chunk) {
    process.stdout.write(update.chunk);  // Coarse path chunks
  }
  if (update.completed) {
    console.log('Final path:', update.path);  // Refined path
  }
}

Types

Type	Description
Buffer	Raw binary image data
Base64EncodedImage	{ imageUrl: string } with base64-encoded image
DetectedObject	Bounding box with x_min, y_min, x_max, y_max
Point	Coordinates with x, y indicating object center
SegmentBbox	Bounding box with x_min, y_min, x_max, y_max
SpatialRef	[x, y] point or [x1, y1, x2, y2] bbox, normalized to [0, 1]

Links

• Website
• Playground
• GitHub