Electron Documentation1.7.8

Docs / API / session


Manage browser sessions, cookies, cache, proxy settings, etc.

Process: Main

The session module can be used to create new Session objects.

You can also access the session of existing pages by using the session property of WebContents, or from the session module.

const {BrowserWindow} = require('electron')

let win = new BrowserWindow({width: 800, height: 600})

const ses = win.webContents.session


The session module has the following methods:

session.fromPartition(partition[, options])

Returns Session - A session instance from partition string. When there is an existing Session with the same partition, it will be returned; otherwise a new Session instance will be created with options.

If partition starts with persist:, the page will use a persistent session available to all pages in the app with the same partition. if there is no persist: prefix, the page will use an in-memory session. If the partition is empty then default session of the app will be returned.

To create a Session with options, you have to ensure the Session with the partition has never been used before. There is no way to change the options of an existing Session object.


The session module has the following properties:


A Session object, the default session object of the app.

Class: Session

Get and set properties of a session.

Process: Main

You can create a Session object in the session module:

const {session} = require('electron')
const ses = session.fromPartition('persist:name')

Instance Events

The following events are available on instances of Session:

Event: ‘will-download’

Emitted when Electron is about to download item in webContents.

Calling event.preventDefault() will cancel the download and item will not be available from next tick of the process.

const {session} = require('electron')
session.defaultSession.on('will-download', (event, item, webContents) => {
  require('request')(item.getURL(), (data) => {
    require('fs').writeFileSync('/somewhere', data)

Instance Methods

The following methods are available on instances of Session:


Callback is invoked with the session’s current cache size.


Clears the session’s HTTP cache.

ses.clearStorageData([options, callback])

Clears the data of web storages.


Writes any unwritten DOMStorage data to disk.

ses.setProxy(config, callback)

Sets the proxy settings.

When pacScript and proxyRules are provided together, the proxyRules option is ignored and pacScript configuration is applied.

The proxyRules has to follow the rules below:

proxyRules = schemeProxies[";"<schemeProxies>]
schemeProxies = [<urlScheme>"="]<proxyURIList>
urlScheme = "http" | "https" | "ftp" | "socks"
proxyURIList = <proxyURL>[","<proxyURIList>]
proxyURL = [<proxyScheme>"://"]<proxyHost>[":"<proxyPort>]

For example:

The proxyBypassRules is a comma separated list of rules described below:

ses.resolveProxy(url, callback)

Resolves the proxy information for url. The callback will be called with callback(proxy) when the request is performed.


Sets download saving directory. By default, the download directory will be the Downloads under the respective app folder.


Emulates network with the given configuration for the session.

// To emulate a GPRS connection with 50kbps throughput and 500 ms latency.
  latency: 500,
  downloadThroughput: 6400,
  uploadThroughput: 6400

// To emulate a network outage.
window.webContents.session.enableNetworkEmulation({offline: true})


Disables any network emulation already active for the session. Resets to the original network configuration.


Sets the certificate verify proc for session, the proc will be called with proc(request, callback) whenever a server certificate verification is requested. Calling callback(0) accepts the certificate, calling callback(-2) rejects it.

Calling setCertificateVerifyProc(null) will revert back to default certificate verify proc.

const {BrowserWindow} = require('electron')
let win = new BrowserWindow()

win.webContents.session.setCertificateVerifyProc((request, callback) => {
  const {hostname} = request
  if (hostname === 'github.com') {
  } else {


Sets the handler which can be used to respond to permission requests for the session. Calling callback(true) will allow the permission and callback(false) will reject it.

const {session} = require('electron')
session.fromPartition('some-partition').setPermissionRequestHandler((webContents, permission, callback) => {
  if (webContents.getURL() === 'some-host' && permission === 'notifications') {
    return callback(false) // denied.



Clears the host resolver cache.


Dynamically sets whether to always send credentials for HTTP NTLM or Negotiate authentication.

const {session} = require('electron')
// consider any url ending with `example.com`, `foobar.com`, `baz`
// for integrated authentication.
session.defaultSession.allowNTLMCredentialsForDomains('*example.com, *foobar.com, *baz')

// consider all urls for integrated authentication.

ses.setUserAgent(userAgent[, acceptLanguages])

Overrides the userAgent and acceptLanguages for this session.

The acceptLanguages must a comma separated ordered list of language codes, for example "en-US,fr,de,ko,zh-CN,ja".

This doesn’t affect existing WebContents, and each WebContents can use webContents.setUserAgent to override the session-wide user agent.


Returns String - The user agent for this session.

ses.getBlobData(identifier, callback)

Returns Blob - The blob data associated with the identifier.


Allows resuming cancelled or interrupted downloads from previous Session. The API will generate a DownloadItem that can be accessed with the will-download event. The DownloadItem will not have any WebContents associated with it and the initial state will be interrupted. The download will start only when the resume API is called on the DownloadItem.

ses.clearAuthCache(options[, callback])

Clears the session’s HTTP authentication cache.

Instance Properties

The following properties are available on instances of Session:


A Cookies object for this session.


A WebRequest object for this session.


A Protocol object for this session.

const {app, session} = require('electron')
const path = require('path')

app.on('ready', function () {
  const protocol = session.fromPartition('some-partition').protocol
  protocol.registerFileProtocol('atom', function (request, callback) {
    var url = request.url.substr(7)
    callback({path: path.normalize(`${__dirname}/${url}`)})
  }, function (error) {
    if (error) console.error('Failed to register protocol')

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