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Technology

Selenium

Difficulty

Advanced

Experience

3-5 Years

Type

Technical

AutomateQA Team

QA Automation Engineers

June 15, 2026

Interview Question

What is Chrome DevTools Protocol (CDP) and how do you use it in Selenium 4?

Answer

Chrome DevTools Protocol (CDP) in Selenium 4

CDP allows Selenium tests to communicate directly with Chrome''s DevTools, enabling capabilities impossible with standard WebDriver commands.

Setup

Java

ChromeDriver driver = new ChromeDriver();
DevTools devTools = driver.getDevTools();
devTools.createSession();

1. Mock Network Conditions (Throttling)

Java

devTools.send(Network.enable(Optional.empty(), Optional.empty(), Optional.empty()));

devTools.send(Network.emulateNetworkConditions(
    false,          // offline
    100,            // latency (ms)
    500 * 1024,     // downloadThroughput (bytes/sec = 500KB/s)
    200 * 1024,     // uploadThroughput
    Optional.of(ConnectionType.CELLULAR3G)
));
driver.get("https://automateqa.online");

2. Block Specific URLs / Requests

Java

devTools.send(Network.setBlockedURLs(List.of("*.png", "*.jpg", "analytics.js")));
driver.get("https://example.com"); // loads without images/analytics

3. Capture Console Logs

Java

devTools.addListener(Log.entryAdded(), entry -> {
    System.out.println("[" + entry.getLevel() + "] " + entry.getText());
});
driver.get("https://example.com");

4. Capture Network Requests/Responses

Java

devTools.send(Network.enable(Optional.empty(), Optional.empty(), Optional.empty()));

devTools.addListener(Network.responseReceived(), response -> {
    System.out.println("URL: " + response.getResponse().getUrl());
    System.out.println("Status: " + response.getResponse().getStatus());
});

5. Override Geolocation

Java

devTools.send(Emulation.setGeolocationOverride(
    Optional.of(51.5074),  // London latitude
    Optional.of(-0.1278),  // London longitude
    Optional.of(1)         // accuracy
));
driver.get("https://maps.google.com");

6. Emulate Device (Mobile)

Java

Map<String, Object> deviceMetrics = new HashMap<>();
deviceMetrics.put("width",  375);
deviceMetrics.put("height", 812);
deviceMetrics.put("mobile", true);
deviceMetrics.put("deviceScaleFactor", 3);

driver.executeCdpCommand("Emulation.setDeviceMetricsOverride", deviceMetrics);

7. Set Authentication Headers

Java

devTools.send(Network.enable(Optional.empty(), Optional.empty(), Optional.empty()));

String credentials = Base64.getEncoder().encodeToString("admin:password".getBytes());
devTools.send(Network.setExtraHTTPHeaders(
    new Headers(Map.of("Authorization", "Basic " + credentials))
));

8. Get Performance Metrics

Java

devTools.send(Performance.enable(Optional.empty()));
List<Metric> metrics = devTools.send(Performance.getMetrics());
metrics.forEach(m -> System.out.println(m.getName() + ": " + m.getValue()));