What is a Hub in Selenium Grid?

A Hub is the central server (or central point) in Selenium Grid that:

1. ✓Receives incoming test execution requests
2. ✓Manages and tracks all registered nodes
3. ✓Routes each test to an appropriate node based on requested capabilities
4. ✓Monitors the overall execution status

Key characteristics:

• ✓There is only ONE Hub per Selenium Grid setup
• ✓Acts as the entry point — test scripts connect to the hub
• ✓Does NOT execute tests itself — delegates to nodes
• ✓Runs on port 4444 by default

Starting the Hub (Selenium 4):

java -jar selenium-server-4.x.jar hub

Hub URL:

http://hub-machine-ip:4444

Connecting a test to the Hub:

RemoteWebDriver driver = new RemoteWebDriver(
    new URL("http://hub-machine-ip:4444"),
    new ChromeOptions()
);

Hub vs Node: