What are DesiredCapabilities in Selenium WebDriver?

DesiredCapabilities is a class in Selenium that stores browser-specific configuration as key-value pairs. It is used to set browser properties such as browser name, version, platform, and SSL certificate handling before launching the driver.

Common use cases:

• ✓Accept SSL certificates
• ✓Set browser version and platform for Selenium Grid
• ✓Enable/disable specific browser features
• ✓Configure remote WebDriver sessions

Chrome example — accept SSL certs:

DesiredCapabilities capabilities = new DesiredCapabilities();
capabilities.setCapability(CapabilityType.ACCEPT_SSL_CERTS, true);
WebDriver driver = new ChromeDriver(capabilities);

Firefox example:

DesiredCapabilities capabilities = DesiredCapabilities.firefox();
capabilities.setBrowserName("firefox");
capabilities.setPlatform(Platform.WINDOWS);

With Selenium Grid:

DesiredCapabilities caps = new DesiredCapabilities();
caps.setBrowserName("chrome");
caps.setPlatform(Platform.LINUX);
RemoteWebDriver driver = new RemoteWebDriver(new URL("http://hub:4444/wd/hub"), caps);

Note: In Selenium 4, DesiredCapabilities is largely replaced by browser-specific Options classes (ChromeOptions, FirefoxOptions). For new projects, prefer Options over DesiredCapabilities.