Why does Katalon clear all cookies when opening browser?

When the automated test has been executed, it will create the new driver instance (FirefoxDrive, ChromeDriver, InternetExplorerDriver, SafariDriver, OperaDriver, HtmlUnitDriver..) instead of the current browser you're using in the manual test, and execute the test under the anonymous profile.

The session of a web driver instance is over once that particular instance is closed. Thus you can't access the session of the previous instance in a new one.

Ref: 

• https://sqa.stackexchange.com/questions/15594/selenium-how-to-access-the-same-session-in-a-new-window

• https://docs.katalon.com/katalon-studio/docs/set-cookies-for-browsers.html

• https://forum.katalon.com/t/fetching-cookie-from-browser-an-use-it-for-calling-rest/14389

• https://stackoverflow.com/questions/54899900/how-to-extract-browser-cookies-using-katalon-studio

Solution 1: Opening Chrome Browser with a predefined custom Chrome Profile which stores session info such as credentials and cookies

import com.kms.katalon.core.webui.driver.DriverFactory
driver = DriverFactory.getWebDriver()
driver.manage().getCookies() // all cookies
driver.manage().getCookieNamed(key) // part of cookies

WebUI.openBrowser('')
Cookie ck = new Cookie("name", "value");
WebDriver driver = DriverFactory.getWebDriver()
driver.manage().addCookie(ck)