OFAC compliance for developers

Developers building payment apps should screen every counterparty against the SDN list before funds move.

TL;DR

TL;DR: For a developer, OFAC compliance is one screening call in the payment path: check the counterparty, return ALLOW or BLOCK, and log the result.

Where screening belongs

Compliance for developers is mostly an engineering problem: put a screening step between the decision to pay and the actual transfer of funds. If the counterparty is flagged, the flow stops. The screening call should be a single HTTP request that returns a decision in under 100 ms so it does not slow the payment.

What to check

Check names against the SDN list and check wallet addresses, because OFAC has listed 947 crypto wallets. The 50 Percent Rule means an entity owned 50% or more by a blocked person is also blocked, so a good tool handles that logic for you. Remember that tools such as x402, AP2, ACP, and Coinbase AgentKit move money but do not screen by themselves.

Getting started

Getting started is low effort. A free tier allows a few checks per day with no signup and no API key, and an MCP server is installable with pip install sanctions-mcp for Claude Code, Cursor, and similar tools. Log every result so you can demonstrate the control later.

A minimal developer checklist

Keep the checklist short: screen the counterparty before the payment, branch on ALLOW or BLOCK, check wallets as well as names, apply the 50 Percent Rule, and log the result. Add the screening call to your payment code the same way you would add any other dependency, then test it with known blocked inputs.