What data is stored
SteamID, name and avatar from the Steam profile, trade URL, listings, deals, balance ledger entries, deposit and withdrawal requests, support tickets, and an administrator action log.
The Steam password is never asked for and is not stored. A user’s Steam API key is not needed and is not saved.
The public seller page shows the name, registration date, deal summary and active listings. Balance, payout details and the full SteamID are not published there.