How to check an address for sanctions free (OFAC / Chainalysis)
Sanctions exposure is the heaviest flag type: if an address is on a sanctions list, the exchange acts under law, not internal policy, with almost no discretion. The good news: you can check an address for sanctions free and in seconds, via the same official sources the exchanges use. Here's how.
Why sanctions are a separate and heavier class of risk
Most AML flags come down to an exchange's internal policy: a risk score, a document request, a P2P complaint. These can be argued with a dossier. Sanctions exposure is a different category: the platform is bound by law, and there is nothing to "negotiate". So checking an address for sanctions before any deal is the cheapest insurance there is.
Two official sources, free to use
OFAC SDN, the US Treasury list
The official list of sanctioned crypto addresses published by the US Office of Foreign Assets Control. It is the primary source exchanges worldwide rely on. Public and officially maintained.
Chainalysis on-chain oracle
Chainalysis (the analytics vendor the exchanges themselves use) deployed a free isSanctioned smart contract across several EVM chains. Anyone can query it directly on-chain, with no registration, no key and no limits. Its data is broader than OFAC alone, covering sanctions regimes of several jurisdictions.
How to check by network
- Ethereum, BSC, Polygon, Arbitrum, Optimism, Avalanche: the Chainalysis oracle answers on all six. It catches a sanctioned address regardless of which chain the funds sit on.
- TRON and Solana: there is no oracle on either, so sanctions are checked against the OFAC list. For USDT, Tether's contract blacklist/freeze also applies.
- The fastest path is our free checker or our Telegram bot @OnyxAML_bot: they query all of these at once and answer in 2 seconds, with plain facts.
How this differs from a paid "risk score"
Paid AML services sell a probabilistic risk percentage. A sanctions check is different: it is a binary fact from an official source, and the address is either on the list or it isn't. We deliberately give that fact for free and don't replace it with an invented "risk percentage". How the exchanges' full scoring works and why it goes deeper is explained in what Chainalysis actually sees.
What to do if an address is sanctioned
If it's a counterparty's address, there should be no deal: accepting funds tied to a sanctioned address means inheriting the heaviest type of risk there is. If your own address, or the one that sent you funds, is sanctioned, that is serious, and "unlockers with a guarantee" are especially dangerous here. Honestly: we don't take cases with a real sanctions trail, because that's a matter of law rather than forensics, and working on them would mean facilitating sanctions evasion. What we take and why we decline is set out in How we work.
Pre-deal checklist
- Check the counterparty's address for sanctions (OFAC + oracle) and against the Tether blacklist; both checks are free.
- Look at the address's basic facts: age, patterns and tags. See how to check an address in 5 minutes.
- If the address is sanctioned or blacklisted, there is no deal, and don't ask for another address: the risk is in the funds, not the address.
- If you have doubts about funds already received, follow the first-24-hours plan.
Bottom line
A sanctions check is no longer a paid-service privilege: the official sources (OFAC + the Chainalysis oracle) are free, and we combined them into one check across TRON, Ethereum, Solana and five more EVM chains. Check with the bot or on the site before a deal: seconds that save you from the heaviest type of freeze.