OFAC SDN Sanctions Screening for Crypto: A Free API Approach

For any crypto business that touches US markets — or that wants to keep its banking relationships — the Office of Foreign Assets Control (OFAC) SDN list is not optional reading. The US Treasury has been designating crypto addresses for years, and banks and exchanges now screen counterparties routinely. One payment to a sanctioned wallet can end a business relationship overnight.

The problem was always cost. Enterprise KYT suites (Chainalysis, Elliptic) run into five figures per year — fine for banks, absurd for a merchant processing a few hundred thousand USDT a month. Until recently, there was no middle ground.

What an OFAC SDN crypto check needs to do

Match the exact address — sanctioned lists contain specific addresses (TRON, BTC, ETH), and the check must be an exact, normalized match with chain detection. No fuzzy guessing.

Cite the source — a compliance officer needs to see why the flag fired: the OFAC designation, or a public incident record. Unlabeled red flags are useless for audits.

Be instant — screening happens in a payment flow. A check that takes minutes is a check that never gets run.

The ChainSentinel approach

ChainSentinel embeds 900+ OFAC SDN addresses (plus verified public-incident wallets) in a local risk-label database — 908 entries total across TRON, BTC, and ETH. The data comes from the US Treasury public-domain SDN list and is re-synced daily.

The public endpoint is POST /api/check:

Send {"address": "0x..."} and receive a level (red/yellow/green), a 0-100 risk score, the reasons, and evidence links in one response — typically under 3 seconds.

On a red hit the response names the exact label and source, e.g. "OFAC SDN" or "Ronin Bridge attack collector". That is the audit trail you need to reject a counterparty defensibly.

Free tier: no API key, rate-limited to 10 checks/min/IP — enough for manual vetting and to test integration. Paid tiers add token-based metering (1,000–10,000 checks/day), webhook alerts, and priority support.

Sanctions screening is a process, not a checkbox

Screening addresses is one layer. Serious operations also monitor their own hot wallets, set up alerts when a counterparty address gets designated later, and keep records of every verdict. ChainSentinel's address monitoring and webhook alerting cover the "designated later" case — the most common way businesses get surprised.

If you are building a payment flow, an OTC desk, or a stablecoin settlement layer, an OFAC SDN check on every counterparty is table stakes. The API above gives you that in a few lines of code.

Need help integrating screening into your workflow, or a custom label database for your jurisdiction? Contact us on Telegram — we respond within hours, Mon–Sat.