How to import Selenium IDE test cases into Katalon Studio
In the Katalon Selenium IDE, select the test case that you want to export. Select File > Save test case as. We need to save the test case as HTML format to import into Katalon Automation Recorder. Provide a name with “.html” and click Save.
Next, to import into Katalon Automation Recorder, start Katalon Automation Recorder extension (Chrome) or addon (Firefox), click 3 vertical dots at the end of Test case explorer, select Open Test Suite from the drop-down menu...
From: https://forum.katalon.com/discussion/4220/how-to-import-selenium-ide-test-cases-into-katalon-studio