> ## Documentation Index
> Fetch the complete documentation index at: https://powersync-diagnostics-docs.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# PowerSync DevTools for Node.js

> Serve PowerSync DevTools from your Node.js app process and open it in a browser.

A Node.js app has no dev server, so your app process serves DevTools and you open it in a browser.

## Requirements

* `@powersync/node`. 
* Node.js 20.16 or later.

## Set Up DevTools

<Steps>
  <Step title="Install the package">
    ```bash theme={null}
    npm install -D @powersync/diagnostics
    ```
  </Step>

  <Step title="Enable DevTools in your app">
    After you create the database, call `enablePowerSyncDiagnostics()` in development only.

    ```typescript theme={null}
    import { PowerSyncDatabase } from '@powersync/node';

    const db = new PowerSyncDatabase({ schema: AppSchema, database: { dbFilename: 'app.db' } });
    await db.connect(connector, { diagnostics: true });

    if (process.env.NODE_ENV !== 'production') {
      const { enablePowerSyncDiagnostics } = await import('@powersync/diagnostics/node');
      const devtools = await enablePowerSyncDiagnostics(db);
      console.log(`PowerSync DevTools: ${devtools.signInUrl}`);
    }
    ```

    Import `@powersync/diagnostics` inside the check. A production install without dev dependencies (`npm ci --omit=dev`) does not include the package. A static import at the top of the file then stops your app at startup.

    `diagnostics: true` is optional. Without it, the **Buckets** tab does not show the total number of operations for each bucket.
  </Step>

  <Step title="Open the sign-in link">
    Start your app and open the link that it prints. The link contains a one-time code that is valid for five minutes and for one browser. If the code expires, open `devtools.url` to print a new link in the terminal.
  </Step>
</Steps>

To see what each tab is for, read [Using DevTools](/tools/devtools/using-devtools). To connect a coding agent to the MCP endpoint at `<url>/__mcp`, read [MCP Tools](/tools/devtools/mcp).

## Options

Pass options as the second argument: `enablePowerSyncDiagnostics(db, { port: 4000 })`.

| Option | Default | Description |
| - | - | - |
| `port` | A random free port | The port that DevTools listens on. A random port makes DevTools harder for other websites to find. |
| `host` | `localhost` | The host that the server binds to. |
| `auth` | `true` | If `true`, the browser must sign in with a one-time code. If `false`, any browser on your machine can open DevTools. |
| `open` | `false` | If `true`, DevTools opens in your browser when the server starts. |
| `sdk` | `@powersync/node` | The SDK label that the UI shows. |
| `id` | `node-1` | The database ID that the UI and the MCP tools show. |
| `mcp` | `'auto'` | The MCP endpoint setting. See [MCP Tools](/tools/devtools/mcp#origin-and-authorization). |

<Warning>
  If you set `host` to an address other than `localhost`, other devices on your network can reach DevTools, which can read and change your local data. In that case, keep `auth` set to `true`.
</Warning>

## Return Value

`enablePowerSyncDiagnostics()` returns an object with these properties:

| Property | Description |
| - | - |
| `url` | The address of DevTools, such as `http://localhost:51234`. |
| `signInUrl` | The link to open. It contains the one-time code. If `auth` is `false`, it is the same as `url`. |
| `close()` | Stops the server and detaches the database. |


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