Why did the exchange freeze my deposit, and how do I avoid it next time?
Exchanges screen every deposit on-chain (known in the industry as KYT, know-your-transaction monitoring). If the coins' upstream traces to a sanctioned address, a mixer, a known scam or stolen funds, the deposit is held until you explain where the money came from. You haven't necessarily done anything wrong — the usual case is that a payment you received had a problematic upstream. To resolve it, give the exchange the source-of-funds evidence it asks for: your dealings with the payer, a contract or order, the payer's address. To avoid it, screen the payer's address before accepting: OceanAlt's free check shows whether it hits a list or carries one-hop taint, and if it does, don't take the payment.
What the exchange looks at
Most exchanges run monitoring from vendors such as Chainalysis, TRM or Elliptic. They look beyond your address at where the funds came from and how many hops away the risk sits. The closer and larger the exposure, the more likely a hold. Thresholds are not public, and the same funds can be treated differently on different platforms.
Checking before you accept
Paste the payer's address into oceanalt.com/en/check: results separate "the payer is itself on a list" from "the payer received funds from a listed address (one-hop taint)", with sources. For a recurring counterparty, put the address on a watchlist to be alerted when its status changes.
The boundary: our screening and an exchange's monitoring don't use the same data, so "no risk signals here" does not guarantee the exchange will accept the deposit. What it does is stop the obvious risks before you take the money.
Where to start: free address check · API docs · watch an address
Boundary of everything above: a screening "clear" only means no match in the data held, never a safety guarantee; this page is not legal or compliance advice.