Look for an exact Codes or Redeem button in the live UI or a developer announcement.
Test the string in-game and record its visible reward and check date.
Ignore code-generator pages, browser extensions and any request for Roblox credentials.
There is no verified code to list right now. The Halloween update and pet event have ended, so EarlyWiki will not turn that past event into a current code claim. Check the update feed for a dated change.