Configuration

info

What you'll learn

• How to configure Cypress to change the default behavior of Cypress
• Configuration options available in Cypress
• How to view and override configuration at runtime

caution

This guide is for Cypress 10+.

For more info on upgrading configuration to Cypress 10, see the migration guide.

Configuration File

Launching Cypress for the first time, you will be guided through a wizard that will create a Cypress configuration file for you. This file will be cypress.config.js for JavaScript apps or cypress.config.ts for TypeScript apps. This file is used to store any configuration specific to Cypress.

Cypress additionally supports config files with .mjs or .cjs extensions.

Using a .mjs file will allow you to use ESM Module syntax in your config without the need of a transpiler step.

A '.cjs' file uses the CommonJS module syntax, which is the default for JavaScript files. All JavaScript config examples in our docs use the CommonJS format.

If you configure your tests to record the results to Cypress Cloud the projectId will be stored in the config file as well.

Intelligent Code Completion

The defineConfig helper function is exported by Cypress, and it provides automatic code completion for configuration in many popular code editors. While it's not strictly necessary for Cypress to parse your configuration, we recommend wrapping your config object with defineConfig() like this:

cypress.config.js

const { defineConfig } = require('cypress')

module.exports = defineConfig({
  e2e: {
    baseUrl: 'http://localhost:1234',
  },
})

cypress.config.ts

import { defineConfig } from 'cypress'

export default defineConfig({
  e2e: {
    baseUrl: 'http://localhost:1234',
  },
})

Options

The default behavior of Cypress can be modified by supplying any of the following configuration options. Below is a list of available options and their default values.

Global

Option	Default	Description
clientCertificates	[]	An optional array of client certificates.
env	{}	Any values to be set as environment variables.
includeShadowDom	false	Whether to traverse shadow DOM boundaries and include elements within the shadow DOM in the results of query commands (e.g. cy.get()).
numTestsKeptInMemory	Default based on run or open mode	The number of tests for which snapshots and command data are kept in memory. numTestsKeptInMemory is set to 50 by default during cypress open and set to 0 by default during cypress run. Reduce this number if you are experiencing high memory consumption in your browser during a test run.
port	null	Port used to host Cypress. Normally this is a randomly generated port.
redirectionLimit	20	The number of times that the application under test can redirect before erroring.
reporter	spec	The reporter used during cypress run.
reporterOptions	null	The reporter options used. Supported options depend on the reporter.
retries	{ "runMode": 0, "openMode": 0 }	The number of times to retry a failing test. Can be configured to apply to cypress run or cypress open separately. As of Cypress 13.4.0, the experimental Flake Detection strategy can also be configured. See Test Retries for more information.
watchForFileChanges	Default based on run or open mode	Whether Cypress will watch and restart tests on test file changes. watchForFileChanges is set to true by default during cypress open and set to false by default during cypress run.

Timeouts

tip

Core Concept

Timeouts are a core concept you should understand well. The default values listed here are meaningful.

Option	Default	Description
defaultCommandTimeout	4000	Time, in milliseconds, to wait until most DOM based commands are considered timed out.
execTimeout	60000	Time, in milliseconds, to wait for a system command to finish executing during a cy.exec() command.
taskTimeout	60000	Time, in milliseconds, to wait for a task to finish executing during a cy.task() command.
pageLoadTimeout	60000	Time, in milliseconds, to wait for page transition events or cy.visit(), cy.go(), cy.reload() commands to fire their page load events. Network requests are limited by the underlying operating system, and may still time out if this value is increased.
requestTimeout	5000	Time, in milliseconds, to wait for a request to go out in a cy.wait() command.
responseTimeout	30000	Time, in milliseconds, to wait until a response in a cy.request(), cy.wait(), cy.fixture(), cy.getCookie(), cy.getCookies(), cy.setCookie(), cy.clearCookie(), cy.clearCookies(), and cy.screenshot() commands.

Folders / Files

Option	Default	Description
downloadsFolder	cypress/downloads	Path to folder where files downloaded during a test are saved.
fileServerFolder	root project folder	Path to folder where application files will attempt to be served from.
fixturesFolder	cypress/fixtures	Path to folder containing fixture files (Pass false to disable).
screenshotsFolder	cypress/screenshots	Path to folder where screenshots will be saved from cy.screenshot() command or after a test fails during cypress run.
videosFolder	cypress/videos	Path to folder where videos will be saved during cypress run.

Screenshots

Option	Default	Description
screenshotOnRunFailure	true	Whether Cypress will take a screenshot when a test fails during cypress run.
screenshotsFolder	cypress/screenshots	Path to folder where screenshots will be saved from cy.screenshot() command or after a test fails during cypress run.
trashAssetsBeforeRuns	true	Whether Cypress will trash assets within the downloadsFolder, screenshotsFolder, and videosFolder before tests run with cypress run.

For more options regarding screenshots, view the Cypress.Screenshot API.

Videos

caution

Currently, Cypress supports video recording for supported Chromium-based browsers (Chrome/Electron/Edge). Support for Firefox can be tracked in this issue.

Option	Default	Description
trashAssetsBeforeRuns	true	Whether Cypress will trash assets within the downloadsFolder, screenshotsFolder, and videosFolder before tests run with cypress run.
videoCompression	false	The quality setting for the video compression, in Constant Rate Factor (CRF). The value can be false or 0 to disable compression or a CRF between 1 and 51, where a lower value results in better quality (at the expense of a higher file size). Setting this option to true will result in a default CRF of 32.
videosFolder	cypress/videos	Where Cypress will automatically save the video of the test run when tests run with cypress run.
video	false	Whether Cypress will capture a video of the tests run with cypress run.

Downloads

Option	Default	Description
downloadsFolder	cypress/downloads	Path to folder where files downloaded during a test are saved.
trashAssetsBeforeRuns	true	Whether Cypress will trash assets within the downloadsFolder, screenshotsFolder, and videosFolder before tests run with cypress run.

Browser

Option	Default	Description
defaultBrowser	null	The default browser to launch if the "--browser" command line option is not provided. This option only affects the first browser launch; changing this option after the browser is already launched will have no effect.
chromeWebSecurity	true	Whether to enable Chromium-based browser's Web Security for same-origin policy and insecure mixed content.
blockHosts	null	A String or Array of hosts that you wish to block traffic for. Please read the notes for examples on using this.
modifyObstructiveCode	true	Whether Cypress will search for and replace obstructive JS code in .js or .html files. Please read the notes for more information on this setting.
userAgent	null	Enables you to override the default user agent the browser sends in all request headers. User agent values are typically used by servers to help identify the operating system, browser, and browser version. See User-Agent MDN Documentation for example user agent values.

Viewport

Option	Default	Description
viewportHeight	660	Default height in pixels for the application under tests' viewport. (Override with cy.viewport() command)
viewportWidth	1000	Default width in pixels for the application under tests' viewport. (Override with cy.viewport() command)

Actionability

Option	Default	Description
animationDistanceThreshold	5	The distance in pixels an element must exceed over time to be considered animating.
waitForAnimations	true	Whether to wait for elements to finish animating before executing commands.
scrollBehavior	top	Viewport position to which an element should be scrolled before executing commands. Can be 'center', 'top', 'bottom', 'nearest', or false. false disables scrolling.

For more information, see the docs on actionability.

Experiments

Configuration might include experimental options currently being tested. See Experiments page.

Testing Type-Specific Options

You can provide configuration options for either E2E or Component Testing by creating e2e and component objects inside your Cypress configuration.

e2e

These options are available to be specified inside the e2e configuration object:

Option	Default	Description
baseUrl	null	URL used as prefix for cy.visit() or cy.request() command's URL.
setupNodeEvents	null	Function in which node events can be registered and config can be modified. Takes the place of the (removed) pluginFile option. Please read the notes for examples on using this.
supportFile	cypress/support/e2e.{js,jsx,ts,tsx}	Path to file to load before spec files load. This file is compiled and bundled. (Pass false to disable)
specPattern	cypress/e2e/**/*.cy.{js,jsx,ts,tsx}	A String or Array of glob patterns of the test files to load.
excludeSpecPattern	*.hot-update.js	A String or Array of glob patterns used to ignore test files that would otherwise be shown in your list of tests. Please read the notes on using this.
experimentalRunAllSpecs	false	Enables the "Run All Specs" UI feature, allowing the execution of multiple specs sequentially.
slowTestThreshold	10000	Time, in milliseconds, to consider a test "slow" during cypress run. A slow test will display in orange text in the default reporter.
testIsolation	true	Whether or not test isolation is enabled to ensure a clean browser context between tests.

cypress.config.js

const { defineConfig } = require('cypress')

module.exports = defineConfig({
  e2e: {
    // e2e options here
  },
})

cypress.config.ts

import { defineConfig } from 'cypress'

export default defineConfig({
  e2e: {
    // e2e options here
  },
})

component

These options are available to be specified inside the component configuration object:

Option	Default	Description
devServer	null	Required option used to configure the component testing dev server. Please read the notes for examples on using this.
indexHtmlFile	cypress/support/component-index.html	This is where Cypress renders your components and allows you to add in global assets, such as styles, fonts, and external scripts.
setupNodeEvents	null	Function in which node events can be registered and config can be modified. Takes the place of the (removed) plugins file. Please read the notes for examples on using this.
supportFile	cypress/support/component.js	Path to file to load before spec files load. This file is compiled and bundled. (Pass false to disable)
specPattern	**/*.cy.{js,jsx,ts,tsx}	A glob pattern String or Array of glob pattern Strings of the spec files to load. Note that any files found matching the e2e.specPattern value will be automatically excluded.
excludeSpecPattern	['/snapshots/*', '/image_snapshots/*']	A String or Array of glob patterns used to ignore spec files that would otherwise be shown in your list of specs. Please read the notes on using this.
experimentalSingleTabRunMode	false	Run all specs in a single tab, instead of creating a new tab per spec. This can improve run mode performance, but can impact spec isolation and reliability on large test suites. This experiment currently only applies to Component Testing.
slowTestThreshold	250	Time, in milliseconds, to consider a test "slow" during cypress run. A slow test will display in orange text in the default reporter.
devServerPublicPathRoute	/__cypress/src	The public path of the dev server in use. Use caution overriding the default value as it can have unintended consequences. See Framework Configuration or dev server specific documentation (in particular @cypress/vite-dev-server).

cypress.config.js

const { defineConfig } = require('cypress')

module.exports = defineConfig({
  component: {
    // component options here
  },
})

cypress.config.ts

import { defineConfig } from 'cypress'

export default defineConfig({
  component: {
    // component options here
  },
})

Overriding Options

Cypress gives you the option to dynamically alter configuration options. This is helpful when running Cypress in multiple environments and on multiple developer machines.

Overriding Individual Options

When running Cypress from the command line you can pass a --config flag to override individual config options.

For example, to override viewportWidth and viewportHeight, you can run:

cypress run --browser firefox --config viewportWidth=1280,viewportHeight=720

Specifying an Alternative Config File

In the Cypress CLI, you can change which config file Cypress will use with the --config-file flag.

cypress run --config-file tests/cypress.config.js

See the Command Line guide for more examples.

Testing Type-Specific Overrides

In addition to setting Testing Type-Specific options, you can override other configuration options for either the E2E Testing or Component Testing.

For example:

cypress.config.js

const { defineConfig } = require('cypress')

module.exports = defineConfig({
  // These settings apply everywhere unless overridden
  defaultCommandTimeout: 5000,
  viewportWidth: 1000,
  viewportHeight: 600,
  // Viewport settings overridden for component tests
  component: {
    viewportWidth: 500,
    viewportHeight: 500,
  },
  // Command timeout overridden for E2E tests
  e2e: {
    defaultCommandTimeout: 10000,
  },
})

cypress.config.ts

import { defineConfig } from 'cypress'

export default defineConfig({
  // These settings apply everywhere unless overridden
  defaultCommandTimeout: 5000,
  viewportWidth: 1000,
  viewportHeight: 600,
  // Viewport settings overridden for component tests
  component: {
    viewportWidth: 500,
    viewportHeight: 500,
  },
  // Command timeout overridden for E2E tests
  e2e: {
    defaultCommandTimeout: 10000,
  },
})

Environment Variables

Configuration options can be overridden with environment variables. This is especially useful in Continuous Integration or when working locally. This gives you the ability to change configuration options without modifying any code or build scripts.

For example, these environment variables in the command line will override any viewportWidth or viewportHeight options set in the Cypress configuration:

export CYPRESS_VIEWPORT_WIDTH=800
export CYPRESS_VIEWPORT_HEIGHT=600

See the Environment Variables guide for more examples.

Test Configuration

We provide two options to override the configuration while your test are running, Cypress.config() and suite-specific or test-specific configuration overrides.

⚠️ Note: The configuration values below are all writeable and can be changed via per test configuration. Any other configuration values are readonly and cannot be changed at run time.

• animationDistanceThreshold
• baseUrl
• blockHosts
• defaultCommandTimeout
• env note: Provided environment variables will be merged with current environment variables.
• execTimeout
• includeShadowDom
• keystrokeDelay
• numTestsKeptInMemory
• pageLoadTimeout
• redirectionLimit
• requestTimeout
• responseTimeout
• retries
• screenshotOnRunFailure
• scrollBehavior
• slowTestThreshold
• taskTimeout
• testIsolation - this option can only be overridden at the suite-specific override level
• viewportHeight
• viewportWidth
• waitForAnimations

Cypress.config()

You can also override configuration values within your test using Cypress.config().

This changes the configuration for the remaining execution of the current spec file. The values will reset to the previous default values after the spec has complete.

Cypress.config('pageLoadTimeout', 100000)

Cypress.config('pageLoadTimeout') // => 100000

Test-specific Configuration

To apply specific Cypress configuration values to a suite or test, pass a configuration object to the test or suite function as the second argument.

The configuration values passed in will only take effect during the suite or test where they are set. The values will then reset to the previous default values after the suite or test is complete.

Syntax

describe(name, config, fn)
context(name, config, fn)
it(name, config, fn)
specify(name, config, fn)

Suite configuration

If you want to target a suite of tests to run or be excluded when run in a specific browser, you can override the browser configuration within the suite configuration. The browser option accepts the same arguments as Cypress.isBrowser().

You can configure the number of times to retries a suite of tests if they fail during cypress run and cypress open separately.

describe(
  'login',
  {
    retries: {
      runMode: 3,
      openMode: 2,
    },
  },
  () => {
    it('should redirect unauthenticated user to sign-in page', () => {
      // ...
    })

    it('allows user to login', () => {
      // ...
    })
  }
)

Single test configuration

If you want to target a test to run or be excluded when run in a specific browser, you can override the browser configuration within the test configuration. The browser option accepts the same arguments as Cypress.isBrowser().

it('Show warning outside Chrome', { browser: '!chrome' }, () => {
  cy.get('.browser-warning').should(
    'contain',
    'For optimal viewing, use Chrome browser'
  )
})

Resolved Configuration

When you open a Cypress project, expanding the Project Settings panel under Settings will display the resolved configuration to you. This helps you to understand and see where different values came from. Each set value is highlighted to show where the value has been set via the following ways:

• Default value
• Cypress configuration file
• The Cypress environment file
• System environment variables
• Command Line arguments
• setupNodeEvents

Notes

blockHosts

By passing a string or array of strings you can block requests made to one or more hosts.

To block a host:

• ✅ Pass only the host
• ✅ Use wildcard * patterns
• ✅ Include the port other than 80 and 443
• ❌ Do NOT include protocol: http:// or https://

info

Not sure what a part of the URL a host is? Use this guide as a reference.

When blocking a host, we use minimatch to check the host. When in doubt you can test whether something matches yourself.

Given the following URLs:

https://www.google-analytics.com/ga.js

http://localhost:1234/some/user.json

This would match the following blocked hosts:

www.google-analytics.com
*.google-analytics.com
*google-analytics.com

localhost:1234

Because localhost:1234 uses a port other than 80 and 443 it must be included.

caution

Subdomains

Be cautious for URL's which have no subdomain.

For instance given a URL: https://google.com/search?q=cypress

• ✅ Matches google.com
• ✅ Matches *google.com
• ❌ Does NOT match *.google.com

When Cypress blocks a request made to a matching host, it will automatically send a 503 status code. As a convenience it also sets a x-cypress-matched-blocked-host header so you can see which rule it matched.

devServer

The devServer option is required for component testing, and allows you to register a component testing dev server.

Typically, you will specify a framework and bundler options in devServer for your framework and UI library like so:

cypress.config.js

const { defineConfig } = require('cypress')

module.exports = defineConfig({
  component: {
    devServer: {
      framework: 'create-react-app',
      bundler: 'webpack',
    },
  },
})

cypress.config.ts

import { defineConfig } from 'cypress'

export default defineConfig({
  component: {
    devServer: {
      framework: 'create-react-app',
      bundler: 'webpack',
    },
  },
})

See Framework Configuration guide for more info on all the available framework and bundler options, as well as additional configuration options.

Custom Dev Server

It is possible to customize the devServer and provide your own function for custom or advanced setups.

The devServer function receives a cypressConfig argument:

cypress.config.js

const { defineConfig } = require('cypress')

module.exports = defineConfig({
  component: {
    devServer(cypressConfig) {
      // return dev server instance or a promise that resolves to
      // a dev server instance here
    },
  },
})

cypress.config.ts

import { defineConfig } from 'cypress'

export default defineConfig({
  component: {
    devServer(cypressConfig) {
      // return dev server instance or a promise that resolves to
      // a dev server instance here
    },
  },
})

See the Custom Dev Server guide for more info.

excludeSpecPattern

Cypress uses minimatch with the options: {dot: true, matchBase: true}. We suggest using https://globster.xyz to test what files would match.

The **/node_modules/** pattern is automatically added to excludeSpecPattern, and does not need to be specified (and can't be overridden). See e2e or component testing-specific options.

isInteractive

You can open Cypress in the interactive mode via the cypress open command, and in run mode via the cypress run command. To detect the mode from your test code you can query the isInteractive property on Cypress.config.

if (Cypress.config('isInteractive')) {
  // interactive "cypress open" mode!
} else {
  // "cypress run" mode
}

modifyObstructiveCode

With this option enabled - Cypress will search through the response streams coming from your server on .html and .js files and replace code that matches patterns commonly found in framebusting.

These script patterns are antiquated and deprecated security techniques to prevent clickjacking and framebusting. They are a relic of the past and are no longer necessary in modern browsers. However many sites and applications still implement them.

These techniques prevent Cypress from working, and they can be safely removed without altering any of your application's behavior.

Cypress modifies these scripts at the network level, and therefore there is a tiny performance cost to search the response streams for these patterns.

You can turn this option off if the application or site you're testing does not implement these security measures. Additionally it's possible that the patterns we search for may accidentally rewrite valid JS code. If that's the case, please disable this option.

Details for experimentalModifyObstructiveThirdPartyCode can be found here.

setupNodeEvents

The setupNodeEvents function allows you to tap into, modify, or extend the internal behavior of Cypress using the on and config arguments, and is valid as an e2e or component testing specific option.

cypress.config.js

const { defineConfig } = require('cypress')

module.exports = defineConfig({
  e2e: {
    setupNodeEvents(on, config) {
      // e2e testing node events setup code
    },
  },
  component: {
    setupNodeEvents(on, config) {
      // component testing node events setup code
    },
  },
})

cypress.config.ts

import { defineConfig } from 'cypress'

export default defineConfig({
  e2e: {
    setupNodeEvents(on, config) {
      // e2e testing node events setup code
    },
  },
  component: {
    setupNodeEvents(on, config) {
      // component testing node events setup code
    },
  },
})

See the plugins guide for more information.

Common problems

baseUrl is not set

Make sure you do not accidentally place the baseUrl config option into the env object. The following configuration is incorrect and will not work:

cypress.config.js

const { defineConfig } = require('cypress')

module.exports = defineConfig({
  // ⛔️ DOES NOT WORK
  env: {
    baseUrl: 'http://localhost:3030',
    FOO: 'bar',
  },
})

cypress.config.ts

import { defineConfig } from 'cypress'

export default defineConfig({
  // ⛔️ DOES NOT WORK
  env: {
    baseUrl: 'http://localhost:3030',
    FOO: 'bar',
  },
})

Solution: place the baseUrl property outside the env object and inside the e2e testing-type specific object.

cypress.config.js

const { defineConfig } = require('cypress')

module.exports = defineConfig({
  // ✅ THE CORRECT WAY
  env: {
    FOO: 'bar',
  },
  e2e: {
    baseUrl: 'http://localhost:3030',
  },
})

cypress.config.ts

import { defineConfig } from 'cypress'

export default defineConfig({
  // ✅ THE CORRECT WAY
  env: {
    FOO: 'bar',
  },
  e2e: {
    baseUrl: 'http://localhost:3030',
  },
})

You can also find a few tips on setting the baseUrl in this short video.

Test files not found when using spec parameter

When using the --spec <path or mask> argument, make it relative to the project's folder. If the specs are still missing, run Cypress with DEBUG logs with the following setting to see how Cypress is looking for spec files:

DEBUG=cypress:cli,cypress:data-context:sources:FileDataSource,cypress:data-context:sources:ProjectDataSource

History

Version	Changes
13.16.0	Added defaultBrowser option.
13.4.0	Added support for configuring the Experimental Flake Detection strategy via retries.experimentalStrategy and retries.experimentalOptions.
13.0.0	Removed nodeVersion option.
13.0.0	Removed videoUploadOnPasses option.
11.0.0	Removed e2e.experimentalSessionAndOrigin option.
10.4.0	Added e2e.testIsolation option.
10.0.0	Reworked page to support new cypress.config.js and deprecated cypress.json files.
8.7.0	Added slowTestThreshold option.
8.0.0	Added clientCertificates option and removed firefoxGcInterval configuration.
7.0.0	Added e2e and component options.
7.0.0	Added redirectionLimit option.
6.1.0	Added scrollBehavior option.
5.2.0	Added includeShadowDom option.
5.0.0	Added retries configuration.
5.0.0	Renamed blacklistHosts configuration to blockHosts.
4.1.0	Added screenshotOnRunFailure configuration.
4.0.0	Added firefoxGcInterval configuration.
3.5.0	Added nodeVersion configuration.

See also

• Cypress.config() and Cypress.env()
• Environment variables
• Environment Variables recipe