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PowerSync SDK for Node.js

PowerSync is a sync engine for building local-first apps with instantly-responsive UI/UX and simplified state transfer. Syncs between SQLite on the client-side and Postgres, MongoDB, MySQL or SQL Server on the server-side.

This package (packages/node) is the PowerSync SDK for Node.js clients. It is an extension of packages/common. Using this package is not necessary for PowerSync on servers, see our documentation for more details on that.

See a summary of features here.

Beta Release​

The @powersync/node package is currently in a Beta release.

Installation​

Install Package​

npm install @powersync/node better-sqlite3

Both @powersync/node and the better-sqlite3 packages have install scripts that need to run to compile or download sqlite3 and PowerSync binaries.

Common Installation Issues​

The better-sqlite package requires native compilation, which depends on certain system tools. This compilation process is handled by node-gyp and may fail if required dependencies are missing or misconfigured.

Node-gyp Version Conflicts​

better-sqlite depends on node-gyp@^11, but some project configurations may introduce multiple versions of node-gyp, potentially causing build issues.

Python Dependency Issues​

node-gyp requires Python for compilation. If your project uses node-gyp below version 10 and your system has Python 3.12 or later, you may encounter the following error:

ModuleNotFoundError: No module named 'distutils'

To resolve this, either:

  • Upgrade node-gyp to version 10 or later.
  • Install Python setuptools, which includes distutils.

Package better-sqlite3 not found errors​

This package does not import better-sqlite3 statically (with unconditional require() or static import statements). Instead, to allow users to use node:sqlite instead of that package, a dynamic require() / import expression is used. This may prevent bundlers from detecting that better-sqlite3 is used by this package.

To fix this, ensure you have a dependency on better-sqlite3 (and, if you're using TypeScript, a dev-dependency on @types/better-sqlite3).

In your project, create a PowerSync.worker.ts file with the following contents:

import Database from 'better-sqlite3';

import { startPowerSyncWorker } from '@powersync/node/worker.js';

async function resolveBetterSqlite3() {
  return Database;
}

startPowerSyncWorker({ loadBetterSqlite3: resolveBetterSqlite3 });

Finally, when you open the PowerSyncDatabase, instruct PowerSync to use your custom worker:

const db = new PowerSyncDatabase({
  schema: AppSchema,
  database: {
    dbFilename: 'test.db',
    openWorker: (_, options) => {
      return new Worker(new URL('./PowerSync.worker.js', import.meta.url), options);
    }
  },
  logger
});

Getting Started​

The Node.js SDK reference contains everything you need to know to get started implementing PowerSync in your project.

Examples​

A simple example using @powersync/node is available in the demos/example-node/ directory.

Proxy Support​

This SDK supports HTTP, HTTPS, and WebSocket proxies via environment variables.

HTTP Connection Method​

Internally we probe the http environment variables and apply it to fetch requests (undici)

  • Set the HTTPS_PROXY or HTTP_PROXY environment variable to automatically route HTTP requests through a proxy.

WEB Socket Connection Method​

Internally the proxy-agent dependency for WebSocket proxies, which has its own internal code for automatically picking up the appropriate environment variables:

  • Set the WS_PROXY or WSS_PROXY environment variable to route the webocket connections through a proxy.

Encryption​

This package can be used with the better-sqlite3-multiple-ciphers fork of better-sqlite3 for encryption.

This requires a custom worker loading the forked package:

// encryption.worker.ts
import Database from 'better-sqlite3-multiple-ciphers';

import { startPowerSyncWorker } from '@powersync/node/worker.js';

async function resolveBetterSqlite3() {
  return Database;
}

startPowerSyncWorker({ loadBetterSqlite3: resolveBetterSqlite3 });

Then, when opening the database, use that custom worker:

const db = new PowerSyncDatabase({
  schema: AppSchema,
  database: {
    dbFilename: 'test.db',
    openWorker: (_, options) => {
      return new Worker(new URL('./PowerSync.worker.js', import.meta.url), options);
    },
    initializeConnection: async (db) => {
      if (encryptionKey.length) {
        const escapedKey = encryptionKey.replace("'", "''");
        await db.execute(`pragma key = '${escapedKey}'`);
      }

      // Make sure the database is readable, this fails early if the key is wrong.
      await db.execute('pragma user_version');
    }
  },
  logger
});

Found a bug or need help?​

  • Join our Discord server where you can browse topics from our community, ask questions, share feedback, or just say hello :)
  • Please open a GitHub issue when you come across a bug.
  • Have feedback or an idea? Submit an idea via our public roadmap or schedule a chat with someone from our product team.

Thanks​

The PowerSync Node.js SDK relies on the work contributors and maintainers have put into the upstream better-sqlite3 package. In particular, we'd like to thank @spinda for contributing support for update, commit and rollback hooks!