How do you maximize a Chrome window without using driver.manage().window().maximize()?

Answer

Maximizing Chrome Window Without maximize()

There are two reliable alternatives when driver.manage().window().maximize() is not preferred or doesn''t work (e.g., in headless mode).

Method 1 — Set Dimension Manually

Java

import org.openqa.selenium.Dimension;

// Set to full HD resolution
Dimension dimension = new Dimension(1920, 1080);
driver.manage().window().setSize(dimension);

Method 2 — ChromeOptions --start-maximized

Java

ChromeOptions options = new ChromeOptions();
options.addArguments("--start-maximized");
// For Linux CI where no screen exists:
options.addArguments("--window-size=1920,1080");

WebDriver driver = new ChromeDriver(options);

Method 3 — Use setPosition + setSize Together

Java

driver.manage().window().setPosition(new Point(0, 0));
driver.manage().window().setSize(new Dimension(1920, 1080));

Method 4 — JavaScript fullscreen

Java

JavascriptExecutor js = (JavascriptExecutor) driver;
js.executeScript("window.moveTo(0, 0);"
    + "window.resizeTo(screen.width, screen.height);");

Headless — Must Use setSize

In headless mode, maximize() often has no effect because there is no physical screen. Always set explicit dimensions:

Java

ChromeOptions options = new ChromeOptions();
options.addArguments("--headless=new");
options.addArguments("--window-size=1920,1080"); // mandatory for headless
WebDriver driver = new ChromeDriver(options);

When to Use Each

Method	Best For
`setSize(new Dimension(...))`	Custom resolution testing
`--start-maximized`	Headed Chrome launch
`--window-size=W,H`	Headless / CI environments
JavaScript resize	Cross-browser fallback