Cliché Finder is a free online tool that marks all clichés in a text.
The tool doesn't require an account. You can simply paste your text in the text box and click on 'Find Clichés'. The tool will mark all cliches red.
Example of an assignment using Cliché Finder:
Open a piece that you wrote and highlight all the clichés you can find. After you have done this, enter the written piece in the Cliché Finder. Did you get them all?