2s.io

● healthy general

Validate a CUSIP (9-character US/Canada securities identifier) with its mod-10 weighted check digit. Returns {valid, cusip, checkDigit, reason}. Catches transposed characters in security master / holdings data that a length check misses. Structure + checksum only. -- reliability 91.0/100 per Paygent Discover

How to call

cURL · x402-fetch / x402-axios will auto-handle 402

curl -X POST https://2s.io

/.well-known/x402.json

https://2s.io/.well-known/x402