When you run tests in Cypress, we launch a browser for you. This enables us to:

Create a clean, pristine testing environment.
Access the privileged browser APIs for automation.

Browsers

When Cypress is initially run from the Test Runner, you can choose to run Cypress in a select number of browsers including:

Cypress automatically detects available browsers on your OS. You can switch the browser in the Test Runner by using the drop down in the top right corner:

Download specific Chrome version

The Chrome browser is evergreen - meaning it will automatically update itself, sometimes causing a breaking change in your automated tests. We host chromium.cypress.io with links to download a specific released version of Chrome (dev, Canary and stable) for every platform.

Electron Browser

In addition to the browsers found on your system, you’ll notice that Electron is an available browser. The Electron browser is a version of Chromium that comes with Electron.

The Electron browser has the advantage of coming baked into Cypress and does not need to be installed separately.

By default, when running cypress run from the CLI, we will launch Electron headlessly.

You can also launch Electron headed:

cypress run --headed

Because Electron is the default browser - it is typically run in CI. If you are seeing failures in CI, to easily debug them you may want to run locally with the --headed option.

Chrome Browsers

All Chrome* flavored browsers will be detected and are supported above Chrome 64.

You can launch Chrome like this:

cypress run --browser chrome

To use this command in CI, you need to install the browser you want - or use one of our docker images.

By default, we will launch Chrome in headed mode. To run Chrome headlessly, you can pass the --headless argument to cypress run.

You can also launch Chromium:

cypress run --browser chromium

Or Chrome Canary:

cypress run --browser chrome:canary

Or Microsoft Edge (Chromium-based):

cypress run --browser edge

Or Microsoft Edge Canary (Chromium-based):

cypress run --browser edge:canary

Firefox Browsers

Firefox-family browsers are supported by Cypress.

You can launch Firefox like this:

cypress run --browser firefox

Or Firefox Developer/Nightly Edition:

cypress run --browser firefox:dev
cypress run --browser firefox:nightly

To use this command in CI, you need to install these other browsers - or use one of our docker images.

By default, we will launch Firefox in headed mode. To run Firefox headlessly, you can pass the --headless argument to cypress run.

Launching by a path

You can launch any supported browser by specifying a path to the binary:

cypress run --browser /usr/bin/chromium

cypress open --browser /usr/bin/chromium

Cypress will automatically detect the type of browser supplied and launch it for you.

See the Command Line guide for more information about the --browser arguments Having trouble launching a browser? Check out our troubleshooting guide

Customize available browsers

Sometimes you might want to modify the list of browsers found before running tests.

For example, your web application might only be designed to work in a Chrome browser, and not inside the Electron browser.

In the plugins file, you can filter the list of browsers passed inside the config object and return the list of browsers you want available for selection during cypress open.

// cypress/plugins/index.js
module.exports = (on, config) => {
  // inside config.browsers array each object has information like
  // {
  //   name: 'chrome',
  //   channel: 'canary',
  //   family: 'chromium',
  //   displayName: 'Canary',
  //   version: '80.0.3966.0',
  //   path:
  //    '/Applications/Canary.app/Contents/MacOS/Canary',
  //   majorVersion: 80
  // }
  return {
    browsers: config.browsers.filter((b) => b.family === 'chromium')
  }
}

When you open the Test Runner in a project that uses the above modifications to your plugins file, only the Chrome browsers found on the system will display in the list of available browsers.

If you return an empty list of browsers or browsers: null, the default list will be restored automatically.

If you have installed a Chromium-based browser like Brave, Vivaldi you can add them to the list of returned browsers. Here is a plugins file that inserts a local Brave browser into the returned list.

// cypress/plugins/index.js
const execa = require('execa')
const findBrowser = () => {
  // the path is hard-coded for simplicity
  const browserPath =
    '/Applications/Brave Browser.app/Contents/MacOS/Brave Browser'

  return execa(browserPath, ['--version']).then((result) => {
    // STDOUT will be like "Brave Browser 77.0.69.135"
    const [, version] = /Brave Browser (\d+\.\d+\.\d+\.\d+)/.exec(
      result.stdout
    )
    const majorVersion = parseInt(version.split('.')[0])

    return {
      name: 'Brave',
      channel: 'stable',
      family: 'chromium',
      displayName: 'Brave',
      version,
      path: browserPath,
      majorVersion
    }
  })
}

module.exports = (on, config) => {
  return findBrowser().then((browser) => {
    return {
      browsers: config.browsers.concat(browser)
    }
  })
}

Once selected, the Brave browser is detected using the same approach as any other browser of the chromium family.

Brave browser executing end-to-end tests

If you modify the list of browsers, you can see the resolved configuration in the Settings tab of the Test Runner.

Unsupported Browsers

Many browsers such as Safari and Internet Explorer are not currently supported. Support for more browsers is on our roadmap. You can read an explanation about our future cross browser roadmap here.

Browser Environment

Cypress launches the browser in a way that’s different from a regular browser environment. But it launches in a way that we believe makes testing more reliable and accessible.

Launching Browsers

When Cypress goes to launch your browser it will give you an opportunity to modify the arguments used to launch the browser.

This enables you to do things like:

Load your own extension
Enable or disable experimental features

This part of the API is documented here.

Cypress Profile

Cypress generates its own isolated profile apart from your normal browser profile. This means things like history entries, cookies, and 3rd party extensions from your regular browsing session will not affect your tests in Cypress.

Wait, I need my developer extensions!
That’s no problem - you have to reinstall them once in the Cypress launched browser. We’ll continue to use this Cypress testing profile on subsequent launches so all of your configuration will be preserved.

Disabled Barriers

Cypress automatically disables certain functionality in the Cypress launched browser that tend to get in the way of automated testing.

The Cypress launched browser automatically:

Ignores certificate errors.
Allows blocked pop-ups.
Disables ‘Saving passwords’.
Disables ‘Autofill forms and passwords’.
Disables asking to become your primary browser.
Disables device discovery notifications.
Disables language translations.
Disables restoring sessions.
Disables background network traffic.
Disables background and renderer throttling.
Disables prompts requesting permission to use devices like cameras or mics
Disables user gesture requirements for autoplaying videos.

You can see all of the default chrome command line switches we send here.

Browser Icon

You might notice that if you already have the browser open you will see two of the same browser icons in your dock.

We understand that when Cypress is running in its own profile it can be difficult to tell the difference between your normal browser and Cypress.

For this reason you may find downloading and using a browser’s release channel versions (Dev, Canary, etc) useful. These browsers have different icons from the standard stable browser, making them more distinguishable. You can also use the bundled Electron browser, which does not have a dock icon.

Additionally, in Chrome-based browsers, we’ve made the browser spawned by Cypress look different than regular sessions. You’ll see a darker theme around the chrome of the browser. You’ll always be able to visually distinguish these.

Troubleshooting

Having issues launching installed browsers? Read more about troubleshooting browser launching