How to set default download directory in selenium Chrome Capabilities?

For Chromedriver try out with:

String downloadFilepath = "/path/to/download";
HashMap<String, Object> chromePrefs = new HashMap<String, Object>();
chromePrefs.put("profile.default_content_settings.popups", 0);
chromePrefs.put("download.default_directory", downloadFilepath);
ChromeOptions options = new ChromeOptions();
options.setExperimentalOption("prefs", chromePrefs);
DesiredCapabilities cap = DesiredCapabilities.chrome();
cap.setCapability(CapabilityType.ACCEPT_SSL_CERTS, true);
cap.setCapability(ChromeOptions.CAPABILITY, options);
WebDriver driver = new ChromeDriver(cap);

Note:- In windows you need to use \\ for path while if you are using linux or mac then use //

Hope this helps. :)

For Python users who see this page -- here's how I set the download directory in Python Selenium (this is just the Python version of Shubham's accepted answer):

def newChromeBrowser(headless=True, downloadPath=None):
    """ Helper function that creates a new Selenium browser """
    options = webdriver.ChromeOptions()
    if headless:
        options.add_argument('headless')
    if downloadPath is not None:
        prefs = {}
        os.makedirs(downloadPath)
        prefs["profile.default_content_settings.popups"]=0
        prefs["download.default_directory"]=downloadPath
        options.add_experimental_option("prefs", prefs)
    browser = webdriver.Chrome(options=options, executable_path=CHROMEDRIVER_PATH)
    return browser

2020 Update:

Chrome: v84

ChromeDriver: v83

JDK: OpenJDK 11 (LTS)

Use Paths class for platform-independent file separators.

@Test
public void doFileDownload() throws Throwable {
    // Since Java 7: Relative path from project root dir
    // Put in target dir to avoid committing downloaded files
    var downloadDir = Paths.get("target").toAbsolutePath().toString();

    var prefs = new HashMap<String, Object>();
    prefs.put("download.default_directory", downloadDir); // Bypass default download directory in Chrome
    prefs.put("safebrowsing.enabled", "false"); // Bypass warning message, keep file anyway (for .exe, .jar, etc.)
    var opts = new ChromeOptions();
    opts.setHeadless(true);
    opts.setExperimentalOption("prefs", prefs);

    var driver = new ChromeDriver(opts); // ChromeDriver binary is added to PATH env var
    driver.manage().timeouts().implicitlyWait(3, TimeUnit.SECONDS);
    driver.manage().window().maximize();
    driver.get("https://the-internet.herokuapp.com/download");

    var downloadLink = driver.findElement(By.cssSelector("a[href*='some-file.txt']"));
    var downloadHref = downloadLink.getAttribute("href").replace(":", "");
    var downloadFileName = Paths.get(downloadHref).getFileName().toString();
    downloadLink.click();

    // Wait download to finish for 60s
    var downloadFilePath = Paths.get(downloadDir, downloadFileName);
    new WebDriverWait(driver, 60).until(d -> downloadFilePath.toFile().exists());

    // Since Java 11: Read content of downloaded file
    var content = Files.readString(downloadFilePath);

    // Do tests with string content...
    log.info("Content={}", content);

    driver.quit();
}

Output:

Doing mvn clean prior to any run also takes care of having to override existing files.

pom.xml:

<properties>
    <!-- Remove encoding warnings -->
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
</properties>

<dependencies>
    <!-- https://mvnrepository.com/artifact/org.seleniumhq.selenium/selenium-server -->
    <dependency>
        <groupId>org.seleniumhq.selenium</groupId>
        <artifactId>selenium-server</artifactId>
        <version>3.141.59</version>
        <scope>test</scope>
    </dependency>
    <!-- https://mvnrepository.com/artifact/org.junit.jupiter/junit-jupiter -->
    <dependency>
        <groupId>org.junit.jupiter</groupId>
        <artifactId>junit-jupiter</artifactId>
        <version>5.6.2</version>
        <scope>test</scope>
    </dependency>
</dependencies>

<build>
    <plugins>
        <!-- https://mvnrepository.com/artifact/org.apache.maven.plugins/maven-compiler-plugin -->
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.8.1</version>
            <configuration>
                <release>11</release>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-surefire-plugin</artifactId>
            <version>2.22.2</version>
        </plugin>
    </plugins>
</build>

The answer which helped me to resolve this issue on Windows: (https://bugs.chromium.org/p/chromedriver/issues/detail?id=783).

Map<String, Object> prefs = new HashMap<String, Object>();
prefs.put("download.default_directory",  System.getProperty("user.dir")+ File.separator + "externalFiles" + File.separator + "downloadFiles");
ChromeOptions options = new ChromeOptions();
options.setExperimentalOption("prefs", prefs);
ChromeDriver driver = new ChromeDriver(options);

For Chrome driver, the below code is worked for me

String downloadFilepath = "/path/to/download";
HashMap<String, Object> chromePrefs = new HashMap<String, Object>();
chromePrefs.put("profile.default_content_settings.popups", 0);
chromePrefs.put("download.default_directory", downloadFilepath);
ChromeOptions options = new ChromeOptions();
options.setExperimentalOption("prefs", chromePrefs);
WebDriver driver = new ChromeDriver(options);