Electron File Download Manager

A simple and easy to use file download manager for Electron applications. Designed in response to the many issues around electron-dl and provides a more robust and reliable solution for downloading files in Electron.

Use cases:

Download files from a URL
Get an id associated with the download to track it
Optionally show a "Save As" dialog
Get progress updates on the download
Be able to cancel / pause / resume downloads
Support multiple downloads at once
Persist downloads when the app closes, allowing them to be restored / resumed later

Electron 26.0.0 or later is required.

// In main process
// Not a working example, just a demonstration of the API
import { ElectronDownloadManager } from 'electron-dl-manager';

const manager = new ElectronDownloadManager();

// Start a download
const id = await manager.download({
  window: browserWindowInstance,
  url: 'https://example.com/file.zip',
  saveDialogOptions: {
    title: 'Save File',
  },
  callbacks: {
    onDownloadStarted: async ({ id, item, webContents }) => {
      // Do something with the download id
    },
    onDownloadProgress: async (...) => {},
    onDownloadCompleted: async (...) => {},
    onDownloadCancelled: async (...) => {},
    onDownloadInterrupted: async (...) => {},
    onError: (err, data) => {},
  }
});

manager.cancelDownload(id);
manager.pauseDownload(id);
manager.resumeDownload(id);

Installation

$ npm install electron-dl-manager

Getting started

You'll want to use electron-dl-manager in the main process of your Electron application where you will be handling the file downloads.

In this example, we use IPC handlers / invokers to communicate between the main and renderer processes, but you can use any IPC strategy you want.

// MainIpcHandlers.ts

import { ElectronDownloadManager } from 'electron-dl-manager';
import { ipcMain } from 'electron';

const manager = new ElectronDownloadManager();

// Renderer would invoke this handler to start a download
ipcMain.handle('download-file', async (event, args) => {
  const { url } = args;

  let downloadId
  const browserWindow = BrowserWindow.fromId(event.sender.id)

  // You *must* call manager.download() with await or 
  // you may get unexpected behavior
  downloadId = await manager.download({
    window: browserWindow,
    url,
    // If you want to download without a save as dialog
    saveAsFilename: 'file.zip',
    directory: '/directory/where/to/save',
    // If you want to download with a save as dialog
    saveDialogOptions: {
      title: 'Save File',
    },
    callbacks: {
      // item is an instance of Electron.DownloadItem
      onDownloadStarted: async ({ id, item, resolvedFilename }) => {
        // Send the download id back to the renderer along
        // with some other data
        browserWindow.webContents.invoke('download-started', {
          id,
          // The filename that the file will be saved as
          filename: resolvedFilename,
          // Get the file size to be downloaded in bytes
          totalBytes: item.getTotalBytes(),
        });
      },
      onDownloadProgress: async ({ id, item, percentCompleted }) => {
        // Send the download progress back to the renderer
        browserWindow.webContents.invoke('download-progress', {
          id,
          percentCompleted,
          // Get the number of bytes received so far
          bytesReceived: item.getReceivedBytes(),
        });
      },
      onDownloadCompleted: async ({ id, item }) => {
        // Send the download completion back to the renderer
        browserWindow.webContents.invoke('download-completed', {
          id,
          // Get the path to the file that was downloaded
          filePath: item.getSavePath(),
        });
      },
      onError: (err, data) => {
        // ... handle any errors
      }
    }
  });

  // Pause the download
  manager.pauseDownload(downloadId);
});

Download Restoration & Persistence

This section covers advanced download management features that go beyond simple pause/resume functionality. These features are essential for applications that need to handle downloads across different browser windows, app restarts, or when downloads are interrupted by external factors.

When to Use These Features

Regular Pause/Resume vs. Restoration

Pause/Resume: Use pauseDownload() and resumeDownload() when you want to temporarily stop and restart a download within the same browser window and session.
Restoration: Use restoreDownload() when you need to resume a download in a different browser window, after the original window has been closed, or when the download manager instance has been destroyed.
Persistence: Use the persistOnAppClose option in download() when you want downloads to automatically survive app restarts, crashes, or when the user closes the application.

Basic Download Restoration

Interface: `RestoreDownloadConfig`

interface RestoreDownloadConfig {
  /**
   * The Electron.App instance
   */
  app: Electron.App
  /**
   * The Electron.BrowserWindow instance where the download should be restored
   */
  window: BrowserWindow
  /**
   * Data required for resuming the download, returned from pauseDownload()
   */
  restoreData: RestoreDownloadData
  /**
   * The callbacks to define to listen for download events
   */
  callbacks: DownloadManagerCallbacks
  /**
   * Electron.DownloadURLOptions to pass to the downloadURL method
   *
   * @see https://www.electronjs.org/docs/latest/api/session#sesdownloadurlurl-options
   */
  downloadURLOptions?: Electron.DownloadURLOptions
}

Interface: `RestoreDownloadData`

interface RestoreDownloadData {
  /**
   * Download id
   */
  id: string
  /**
   * The URL of the download
   */
  url: string
  /**
   * The path and filename where the download will be saved
   */
  fileSaveAsPath: string
  /**
   * The chain of URLs that led to this download
   */
  urlChain: string[]
  /**
   * The MIME type of the file being downloaded
   */
  mimeType: string
  /**
   * The ETag of the download, if available. This is used to resume downloads
   */
  eTag: string
  /**
   * The number of bytes already received
   */
  receivedBytes: number
  /**
   * The total number of bytes to download
   */
  totalBytes: number
  /**
   * The timestamp when the download started
   */
  startTime: number
  /**
   * The percentage of the download that has been completed
   */
  percentCompleted: number
  /**
   * If persistOnAppClose is true, this is the path where the download
   * is persisted to. This is used to restore the download later.
   */
  persistedFilePath?: string
}

Example: Basic Download Restoration

// Pause a download and get restore data
const restoreData = manager.pauseDownload(downloadId);

if (restoreData) {
  // Later, in a different browser window
  const newDownloadId = await manager.restoreDownload({
    app,
    window: newBrowserWindow,
    restoreData,
    callbacks: {
      onDownloadStarted: async ({ id, item, resolvedFilename }) => {
        console.log(`Restored download ${id} started`);
      },
      onDownloadProgress: async ({ id, percentCompleted }) => {
        console.log(`Restored download ${id} progress: ${percentCompleted}%`);
      },
      onDownloadCompleted: async ({ id, item }) => {
        console.log(`Restored download ${id} completed`);
      },
      onError: (err, data) => {
        console.error('Error in restored download:', err);
      }
    }
  });
}

Download Persistence

Version 4.2.0 introduces the ability to automatically persist downloads when the application closes, allowing them to be restored later. This feature is fundamentally different from manual pause/resume because it:

Automatically triggers when the app is about to close (listens to the will-quit event)
Preserves download state including progress, file paths, and metadata
Survives app crashes and unexpected shutdowns
Works across app restarts without requiring user intervention
Handles file management by creating temporary .download files that are automatically restored

Enabling Download Persistence

To enable download persistence, set persistOnAppClose: true and provide the app instance:

const id = await manager.download({
  app, // Electron.App instance
  window: mainWindow,
  url: 'https://example.com/large-file.zip',
  saveAsFilename: 'large-file.zip',
  persistOnAppClose: true,
  callbacks: {
    onDownloadPersisted: async (data, restoreData) => {
      console.log('Download persisted:', restoreData.persistedFilePath);
      // Save restoreData to a file or database for later restoration
      writeFileSync('download-metadata.json', JSON.stringify(restoreData));
    },
    onDownloadCompleted: async (data) => {
      console.log('Download completed');
    },
    onError: (err, data) => {
      console.error('Download error:', err);
    }
  }
});

Restoring Persisted Downloads

When the app restarts, you can restore persisted downloads using the saved metadata:

// Read the saved metadata
const metadata = JSON.parse(readFileSync('download-metadata.json', 'utf-8'));

// Restore the download
await manager.restoreDownload({
  app,
  window: mainWindow,
  restoreData: metadata,
  callbacks: {
    onDownloadStarted: async (data) => {
      console.log('Persisted download restored and started');
    },
    onDownloadProgress: async (data) => {
      console.log(`Progress: ${data.percentCompleted}%`);
    },
    onDownloadCompleted: async (data) => {
      console.log('Persisted download completed');
    },
    onError: (err, data) => {
      console.error('Error in restored download:', err);
    }
  }
});

Note: The persistedFilePath in the restore data points to a temporary file with a .download extension. The library automatically handles moving this file to the correct location when restoring.

API

Class: `ElectronDownloadManager`

Manages file downloads in an Electron application.

`constructor()`

constructor(params: DownloadManagerConstructorParams)

interface DownloadManagerConstructorParams {
  /**
   * If defined, will log out internal debug messages. Useful for
   * troubleshooting downloads. Does not log out progress due to
   * how frequent it can be.
   */
  debugLogger?: (message: string) => void
}

`download()`

Starts a file download. Returns the id of the download.

download(params: DownloadParams): Promise<string>

Interface: `DownloadParams`

interface DownloadParams {
  /**
   * The Electron.BrowserWindow instance
   */
  window: BrowserWindow
  /**
   * The URL to download
   */
  url: string
  /**
   * The callbacks to define to listen for download events
   */
  callbacks: DownloadManagerCallbacks
  /**
   * Electron.DownloadURLOptions to pass to the downloadURL method
   *
   * @see https://www.electronjs.org/docs/latest/api/session#sesdownloadurlurl-options
   */
  downloadURLOptions?: Electron.DownloadURLOptions
  /**
   * If defined, will show a save dialog when the user
   * downloads a file.
   *
   * @see https://www.electronjs.org/docs/latest/api/dialog#dialogshowsavedialogbrowserwindow-options
   */
  saveDialogOptions?: SaveDialogOptions
  /**
   * The filename to save the file as. If not defined, the filename
   * from the server will be used.
   *
   * Only applies if saveDialogOptions is not defined.
   */
  saveAsFilename?: string
  /**
   * The directory to save the file to. Must be an absolute path.
   * @default The user's downloads directory
   */
  directory?: string
  /**
   * If true, will overwrite the file if it already exists
   * @default false
   */
  overwrite?: boolean
  /**
   * If true, will persist the download when the app closes, allowing it to be restored later.
   * Requires the `app` parameter to be provided.
   * @default false
   */
  persistOnAppClose?: boolean
  /**
   * The Electron.App instance. Required if persistOnAppClose is enabled.
   */
  app?: Electron.App
}

Interface: `DownloadManagerCallbacks`

interface DownloadManagerCallbacks {
  /**
   * When the download has started. When using a "save as" dialog,
   * this will be called after the user has selected a location.
   *
   * This will always be called first before the progress and completed events.
   */
  onDownloadStarted: (data: DownloadData) => void
  /**
   * When there is a progress update on a download. Note: This
   * may be skipped entirely in some cases, where the download
   * completes immediately. In that case, onDownloadCompleted
   * will be called instead.
   */
  onDownloadProgress: (data: DownloadData) => void
  /**
   * When the download has completed
   */
  onDownloadCompleted: (data: DownloadData) => void
  /**
   * When the download has been cancelled. Also called if the user cancels
   * from the save as dialog.
   */
  onDownloadCancelled: (data: DownloadData) => void
  /**
   * When the download has been interrupted. This could be due to a bad
   * connection, the server going down, etc.
   */
  onDownloadInterrupted: (data: DownloadData) => void
  /**
   * When the download has been persisted for later restoration.
   * This callback is called when persistOnAppClose is enabled and the app is about to close.
   */
  onDownloadPersisted?: (data: DownloadData, restoreDownloadData: RestoreDownloadData) => void
  /**
   * When an error has been encountered.
   * Note: The signature is (error, <maybe some data>).
   */
  onError: (error: Error, data?: DownloadData) => void
}

`cancelDownload()`

Cancels a download.

cancelDownload(id: string): void

`pauseDownload()`

Pauses a download and returns the data necessary to restore it later via restoreDownload().

pauseDownload(id: string): RestoreDownloadData | undefined

Returns: RestoreDownloadData if the download exists and can be paused, undefined if the download is not found.

Note: Use the returned data with restoreDownload() to restore a download.

`resumeDownload()`

Resumes a download.

resumeDownload(id: string): void

`restoreDownload()`

Restores a download that is not registered in the download manager using data returned from pauseDownload(). This is useful when you need to restore a download in a different browser window or after the original window has been closed.

If the download is already registered in the current download manager, this method will call resumeDownload() instead.

restoreDownload(params: RestoreDownloadConfig): Promise<string>

Note: See the Download Restoration & Persistence section for detailed information about restoring downloads and using the persistence feature.

`getActiveDownloadCount()`

Returns the number of active downloads.

getActiveDownloadCount(): number

`getDownloadData()`

Returns the download data for a download.

getDownloadData(id: string): DownloadData

Class: `DownloadData`

Data returned in the callbacks for a download.

Properties

class DownloadData {
  /**
   * Generated id for the download
   */
  id: string
  /**
   * The Electron.DownloadItem. Use this to grab the filename, path, etc.
   * @see https://www.electronjs.org/docs/latest/api/download-item
   */
  item: DownloadItem
  /**
   * The Electron.WebContents
   * @see https://www.electronjs.org/docs/latest/api/web-contents
   */
  webContents: WebContents
  /**
   * The Electron.Event
   * @see https://www.electronjs.org/docs/latest/api/event
   */
  event: Event
  /**
   * The name of the file that is being saved to the user's computer.
   * Recommended over Item.getFilename() as it may be inaccurate when using the save as dialog.
   */
  resolvedFilename: string
  /**
   * If true, the download was cancelled from the save as dialog. This flag
   * will also be true if the download was cancelled by the application when
   * using the save as dialog.
   */
  cancelledFromSaveAsDialog?: boolean
  /**
   * The percentage of the download that has been completed
   */
  percentCompleted: number
  /**
   * The download rate in bytes per second.
   */
  downloadRateBytesPerSecond: number
  /**
   * The estimated time remaining in seconds.
   */
  estimatedTimeRemainingSeconds: number
  /**
   * If the download was interrupted, the state in which it was interrupted from
   */
  interruptedVia?: 'in-progress' | 'completed'
  /**
   * If defined, this is the path where the download is persisted to.
   * This is set when persistOnAppClose is enabled and the download is persisted.
   */
  persistedFilePath?: string
}

Formatting download progress

You can use the libraries bytes and dayjs to format the download progress.

$ pnpm add bytes dayjs
$ pnpm add -D @types/bytes

import bytes from 'bytes'
import dayjs from 'dayjs'
import relativeTime from 'dayjs/plugin/relativeTime';
import duration from 'dayjs/plugin/duration';

dayjs.extend(relativeTime);
dayjs.extend(duration);

const downloadData = manager.getDownloadData(id); // or DataItem from the callbacks

// Will return something like 1.2 MB/s
const formattedDownloadRate = bytes(downloadData.downloadRateBytesPerSecond, { unitSeparator: ' ' }) + '/s'

// Will return something like "in a few seconds"
const formattedEstimatedTimeRemaining = dayjs.duration(downloadData.estimatedTimeRemainingSeconds, 'seconds').humanize(true)

`isDownloadInProgress()`

Returns true if the download is in progress.

isDownloadInProgress(): boolean

`isDownloadPaused()`

Returns true if the download is paused.

isDownloadPaused(): boolean

`isDownloadResumable()`

Returns true if the download is resumable.

isDownloadResumable(): boolean

`isDownloadCancelled()`

Returns true if the download is cancelled.

isDownloadCancelled(): boolean

`isDownloadInterrupted()`

Returns true if the download is interrupted.

isDownloadInterrupted(): boolean

`isDownloadCompleted()`

Returns true if the download is completed.

isDownloadCompleted(): boolean

`getRestoreDownloadData()`

Returns the data necessary to restore this download later via restoreDownload(). This method is typically called after pausing a download to get the data needed for restoration.

getRestoreDownloadData(): RestoreDownloadData

Returns: RestoreDownloadData containing all the information needed to restore the download, including the file path, URL, MIME type, ETag, and byte information.

Mock class

If you need to mock out ElectronDownloadManager in your tests, you can use the ElectronDownloadManagerMock class.

import { ElectronDownloadManagerMock } from 'electron-dl-manager'

FAQ

How do I capture if the download is invalid? `onError()` is not being called.

Electron DownloadItem doesn't provide an explicit way to capture errors for downloads in general:

https://www.electronjs.org/docs/latest/api/download-item#class-downloaditem

(It only has on('updated') and on('done') events, which this library uses for defining the callback handlers.)

What it does for invalid URLs, it will trigger the onDownloadCancelled() callback.

const id = await manager.download({
  window: mainWindow,
  url: 'https://alkjsdflksjdflk.com/file.zip',
  callbacks: {
    onDownloadCancelled: async (...) => {
      // Invalid download; this callback will be called
    },
  }
});

A better way to handle this is to check if the URL exists prior to the download yourself. I couldn't find a library that I felt was reliable to include into this package, so it's best you find a library that works for you:

https://www.npmjs.com/search?q=url%20exists&ranking=maintenance

GPT also suggests the following code (untested):

async function urlExists(url: string): Promise<boolean> {
  try {
    const response = await fetch(url, { method: 'HEAD' });
    return response.ok;
  } catch (error) {
    return false;
  }
}

const exists = await urlExists('https://example.com/file.jpg');

Acknowledgments

This code uses small portions from electron-dl and is noted in the code where it is used.

electron-dl is licensed under the MIT License and is maintained by Sindre Sorhus sindresorhus@gmail.com (https://sindresorhus.com).

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src		src
test		test
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CHANGELOG.md		CHANGELOG.md
LICENSE		LICENSE
README.md		README.md
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commitlint.config.js		commitlint.config.js
lefthook.yml		lefthook.yml
package.json		package.json
pnpm-lock.yaml		pnpm-lock.yaml
syncpack.config.js		syncpack.config.js
tsconfig.json		tsconfig.json
tsup.config.json		tsup.config.json
vitest.config.ts		vitest.config.ts

License

theogravity/electron-dl-manager

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Electron File Download Manager

Table of contents

Installation

Getting started

Download Restoration & Persistence

When to Use These Features

Regular Pause/Resume vs. Restoration

Basic Download Restoration

Interface: RestoreDownloadConfig

Interface: RestoreDownloadData

Example: Basic Download Restoration

Download Persistence

Enabling Download Persistence

Restoring Persisted Downloads

API

Class: ElectronDownloadManager

constructor()

download()

Interface: DownloadParams

Interface: DownloadManagerCallbacks

cancelDownload()

pauseDownload()

resumeDownload()

restoreDownload()

getActiveDownloadCount()

getDownloadData()

Class: DownloadData

Properties

Formatting download progress

isDownloadInProgress()

isDownloadPaused()

isDownloadResumable()

isDownloadCancelled()

isDownloadInterrupted()

isDownloadCompleted()

getRestoreDownloadData()