Always be aware of api scams.

When trading with someone on steam (who you may know very well, it may even be yourself) a ♥♥♥ will instantly create a steam account with the profile picture of the account you are trading with, the original offer will be cancelled and it will prompt you to confirm a trade with the fake account. It should give you a scam warning message that a trade has just been cancelled, DO NOT DISREGARD THIS!!

Stay safe