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VectorDB.js — Simple in-memory vector database for Node.js


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VectorDB.js is a simple in-memory vector database for Node.js. It’s an easy way to do text similarity.


Install VectorDB.js from NPM:

npm install @themaximalist/vectordb.js

For local embeddings, install the transformers library:

npm install @xenova/transformers

For remote embeddings like OpenAI and Mistral, add an API key to your environment.

export OPENAI_API_KEY=...
export MISTRAL_API_KEY=...


To find similar strings, add a few to the database, and then search.

import VectorDB from "@themaximalist/vectordb.js"
const db = new VectorDB();

await db.add("orange");
await db.add("blue");

const result = await"light orange");
// [ { input: 'orange', distance: 0.3109036684036255 } ]

Embedding Models

By default VectorDB.js uses a local embeddings model.

To switch to another model like OpenAI, pass the service to the embeddings config.

const db = new VectorDB({
  dimensions: 1536,
  embeddings: {
    service: "openai"

await db.add("orange");
await db.add("blue");
await db.add("green");
await db.add("purple");

// ask for up to 4 embeddings back, default is 3
const results = await"light orange", 4);
assert(results.length === 4);
assert(results[0].input === "orange");

With Mistral Embeddings:

const db = new VectorDB({
  dimensions: 1024,
  embeddings: {
    service: "mistral"

// ...

Being able to easily switch embeddings providers ensures you don’t get locked in!

VectorDB.js was built on top of Embeddings.js, and passes the full embeddings config option to Embeddings.js.

Custom Objects

VectorDB.js can store any valid JavaScript object along with the embedding.

const db = new VectorDB();

await db.add("orange", "oranges");
await db.add("blue", ["sky", "water"]);
await db.add("green", { "grass": "lawn" });
await db.add("purple", { "flowers": 214 });

const results = await"light green", 1);
assert(results[0].object.grass == "lawn");

This makes it easy to store metadata about the embedding, like an object id, URL, etc…


The VectorDB.js library offers a simple API for using vector databases. To get started, initialize the VectorDB class with a config object.

new VectorDB({
  dimensions: 384, // Default: 384. The dimensionality of the embeddings.
  size: 100,       // Default: 100. Initial size of the database; automatically resizes
  embeddings: {
    service: "openai" // Configuration for the embeddings service.



async add(input=<string>, obj=<object>)

Adds a new text string to the database, with an optional JavaScript object.

await vectordb.add("Hello World", { dbid: 1234 });

async search(input=<string>, num=<int>, threshold=<float>)

Search the vector database for a string input, no more than num and only if the distance is under threshold.

// 5 results closer than 0.5 distance
await"Hello", 5, 0.5);


Resizes the database to specific size, handled automatically but can be set explicitly.



VectorDB.js returns results from as a simple array of objects that follow this format:

      input: "Red"
      distance: 0.54321,
      object: {
        dbid: 123


VectorDB.js uses the debug npm module with the vectordb.js namespace.

View debug logs by setting the DEBUG environment variable.

> DEBUG=vectordb.js*
> node src/run_vector_search.js
# debug logs

The VectorDB.js API aims to make it simple to do text similarity in Node.js—without getting locked into an expensive cloud provider or embedding model.


VectorDB.js works great by itself, but was built side-by-side to work with Model Deployer.

Model Deployer is an easy way to deploy your LLM and Embedding models in production. You can monitor usage, rate limit users, generate API keys with specific settings and more.

It’s especially helpful in offering options to your users. They can download and run models locally, they can use your API, or they can provide their own API key.

It works out of the box with VectorDB.js.

const db = new VectorDB({
  embeddings: {
    service: "modeldeployer",
    model: "api-key",

await db.add("orange", "oranges");
await db.add("blue", ["sky", "water"]);
await db.add("green", { "grass": "lawn" });
await db.add("purple", { "flowers": 214 });

const results = await"light green", 1);
assert(results[0].object.grass == "lawn");

Learn more about deploying embeddings with Model Deployer.


VectorDB.js is currently used in the following projects:




Created by The Maximalist, see our open-source projects.