You're in the right to leave the code online as a part of your portfolio so long as you didn't sign a contract with them and they didn't pay you for the work.
You should, however, not include their company name in your code or descriptions.
You should, however, not include their company name in your code or descriptions.
Upvotes suffice and moves the response to the top, letting everyone know it's the favored comment. 'this' will get you negative karma eventually.