Holster is a real-time data synchronisation service that connects devices using Node.js, Deno, Bun or the browser. Built with ES modules, it features end-to-end encryption, conflict resolution and cross-platform compatibility.

✨ Real-time sync across all connected devices
🔐 Built-in encryption with user authentication
⚡ Zero configuration with smart performance optimisation
🌐 Universal compatibility - works everywhere JavaScript runs

Try it out at holster.haza.website!

A build version of Holster is also provided using esbuild, to run in production.

Check out the Github Wiki for how to get started using the API, and for more information.

Quick Start

• Clone this repo

Then using Docker

• Run docker build -t holster . to build the image
• Run docker run -p 3000:3000 -p 8765:8765 holster to start the server

Or run locally

• Run npm install
• Run the server with node src/index.js

Once the server is running

• Open http://localhost:3000/examples/index.html in the browser.
• You will then also have access to the Holster API via the holster object in the console

How to run a Holster relay

To run a Holster relay, create a relay.js file with:

import Holster from "@mblaney/holster/src/holster.js"
Holster({port: 8765})

That's all you need to run a server on port 8765. You may also want to pass in memory and storage options with larger values than the defaults, which are conservative to support browser use. See Holster options for more details. To run this with node:

• npm install
• node relay.js

For production you can start with pm2:

• npm install pm2 -g
• export NODE_ENV=production
• pm2 startup (And follow startup instructions.)
• pm2 start relay.js
• pm2 save

To allow connections via a web server see examples/apache.md.

Related packages

holster-router provides an Express router for building web applications with Holster, including user account management and email integration.

Development

• When modifying files run: npx prettier . --write
• To run the JavaScript tests use: npm run test
• To run the TypeScript tests use: npm run test:ts