Validate the check digit of a financial security identifier
Validate the check digit of a financial security identifier: ISIN (ISO 6166), CUSIP, SEDOL and FIGI. Returns the verdict, the computed correct check character, and for an ISIN the issuing country prefix and the embedded NSIN. Also builds an ISIN from a country code plus a 9-character NSIN. Format and checksum only, no security master lookup.
Answeringour last check, 2026-09-29
1 of 1checks answered this week
21 msmedian answer time
$0.05listed price per call
$0.05price it asked us
Paid test badge: not yet. The checks above are free: we call the tool without paying and read the payment request it sends back. The Verified badge needs paid calls whose answers match the promised output, and nobody can buy a badge.
Endpoint
GET https://api.duoleads.com/v1/id/security
| Category | Code and developer |
|---|---|
| Provider host | api.duoleads.com |
| Networks | eip155:8453 |
| Payment schemes | exact |
| Self-reported calls, 30 days | 1 from 1 payers (the provider's figure, not ours) |
Our checks, last 30 days
| Day | Result | HTTP | Asked | Time |
|---|---|---|---|---|
| 2026-09-29 | valid payment request | 402 | $0.05 | 21 ms |
Example input (from the provider)
{
"method": "GET",
"queryParams": {
"value": "US0378331005"
},
"type": "http"
}
Promised output schema (from the provider)
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": false,
"properties": {
"method": {
"enum": [
"GET"
],
"type": "string"
},
"queryParams": {
"properties": {
"country": {
"description": "ISO 3166-1 alpha-2 code or XS. Required when op=build-isin.",
"maxLength": 16,
"type": "string"
},
"nsin": {
"description": "Exactly 9 alphanumeric characters. Required when op=build-isin.",
"maxLength": 64,
"type": "string"
},
"op": {
"default": "validate",
"description": "validate (default) or build-isin.",
"enum": [
"validate",
"build-isin"
],
"maxLength": 64,
"type": "string"
},
"value": {
"description": "ISIN, CUSIP, SEDOL or FIGI to validate. Required when op=validate.",
"maxLength": 24,
"type": "string"
}
},
"required": [],
"type": "object"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method"
],
"type": "object"
},
"output": {
"properties": {
"example": {
"properties": {
"data": {
"type": "object"
},
"meta": {
"properties": {
"computed_at": {
"type": "string"
},
"deterministic": {
"type": "boolean"
},
"disclaimer": {
"type": "string"
},
"price_usd": {
"type": "string"
},
"request_id": {
"type": "string"
},
"sources": {
"type": "array"
}
},
"required": [
"request_id",
"computed_at",
"price_usd",
"deterministic",
"disclaimer"
],
"type": "object"
},
"ok": {
"const": true,
"type": "boolean"
},
"route": {
"type": "string"
},
"version": {
"type": "string"
}
},
"required": [
"ok",
"route",
"version",
"data",
"meta"
],
"type": "object"
},
"type": {
"type": "string"
}
},
"required": [
"type"
],
"type": "object"
}
},
"required": [
"input"
],
"type": "object"
}