CUSIP

GET/v0/cusip

Validates a CUSIP (Committee on Uniform Security Identification Procedures) identifier — the 9-character code used to identify financial instruments in the United States and Canada. A CUSIP consists of a 6-character issuer number, a 2-character issue number, and a 1-digit check digit computed using a modified Luhn algorithm with a character-to-number mapping that covers digits 0–9, letters A–Z, and special characters *, @, and #. Whitespace in the input is stripped automatically.

When the CUSIP is structurally valid, the endpoint looks up instrument details from two sources simultaneously. OpenFIGI (Bloomberg) is queried directly with the CUSIP. ESMA FIRDS (the EU regulatory reference database under MiFID II, synchronised daily) is queried via the derived US ISIN (US + CUSIP + Luhn check digit). Both sources are queried in parallel and their fields are merged into a single response. The dataSource field indicates which source(s) returned data: firds, openfigi, or firds+openfigi when both found the instrument. Fields from an unavailable or non-matching source are returned as null. OpenFIGI results are cached for 24 hours.

For US and Canadian ISINs the NSIN is identical to the CUSIP, so the /v0/isin endpoint also returns a cusip field derived from the ISIN NSIN when the country code is US or CA.

Guides: Node.js · Python

Try it

Query Parameters

Parameter	Type	Required	Description
value	string	Yes	The 9-character CUSIP to validate (e.g. `037833100`)

Example Request

curl -H "Authorization: Bearer YOUR_API_KEY" \
  "https://api.isvalid.dev/v0/cusip?value=037833100"

Response Fields

Field	Type	Description
valid	boolean	Whether the CUSIP passed format and check digit validation
issuerNumber	string	First 6 characters identifying the issuer, assigned by the CUSIP Global Services bureau
issueNumber	string	Characters 7–8 identifying the specific issue (share class, bond series, etc.)
checkDigit	string	The check digit (9th character, always a digit 0–9)
isin	string	US ISIN derived from the CUSIP (`US` + CUSIP + Luhn check digit), e.g. `US0378331005`
found	boolean \| null	Whether the instrument was found in any data source. `true` — found, instrument details included; `false` — structurally valid CUSIP but not found in either source; `null` — all data sources unavailable, structural validation result only
dataSource	string	Which source(s) found the instrument. `firds` — ESMA FIRDS only; `openfigi` — OpenFIGI only; `firds+openfigi` — both sources returned data (fields from each are merged). Present only when `found` is `true`
name	string \| null	Full instrument name (e.g. `Apple Inc.`). Present when `found` is `true`
fisn	string \| null	Financial Instrument Short Name (ISO 18774), e.g. `APPLE INC/SH SH`. From FIRDS; `null` when FIRDS data is unavailable
status	string \| null	Instrument lifecycle status from FIRDS. `ACTV` — active; `TERM` — terminated (delisted or expired). Present when `found` is `true`; `null` when FIRDS data is unavailable
cfiCode	string \| null	6-character Classification of Financial Instruments code (ISO 10962), e.g. `ESVUFR` for equity. From FIRDS; `null` when FIRDS data is unavailable
currency	string \| null	ISO 4217 notional currency code (e.g. `USD`). From FIRDS; `null` when FIRDS data is unavailable
tradingVenue	string \| null	ISO 10383 Market Identifier Code (MIC) of the primary trading venue (e.g. `XNAS` for NASDAQ). From FIRDS; `null` when FIRDS data is unavailable
issuerLei	string \| null	Legal Entity Identifier (LEI) of the instrument issuer. From FIRDS; `null` when FIRDS data is unavailable
maturityDate	string \| null	Maturity or expiry date in `YYYY-MM-DD` format for bonds and derivatives. From FIRDS; `null` for equities or when FIRDS data is unavailable
ticker	string \| null	Exchange ticker symbol (e.g. `AAPL`). From OpenFIGI; `null` when OpenFIGI data is unavailable
exchCode	string \| null	Bloomberg exchange code (e.g. `US`). From OpenFIGI; `null` when OpenFIGI data is unavailable
securityType	string \| null	Security type from OpenFIGI (e.g. `Common Stock`). From OpenFIGI; `null` when OpenFIGI data is unavailable
marketSector	string \| null	Market sector from OpenFIGI (e.g. `Equity`). From OpenFIGI; `null` when OpenFIGI data is unavailable
figi	string \| null	Financial Instrument Global Identifier (e.g. `BBG000B9XRY4`). From OpenFIGI; `null` when OpenFIGI data is unavailable
compositeFIGI	string \| null	Composite FIGI representing the instrument across all exchanges. From OpenFIGI; `null` when OpenFIGI data is unavailable or the instrument has no composite FIGI

Example Response — found in both sources

{
  "valid": true,
  "issuerNumber": "037833",
  "issueNumber": "10",
  "checkDigit": "0",
  "isin": "US0378331005",
  "found": true,
  "dataSource": "firds+openfigi",
  "name": "Apple Inc.",
  "fisn": "APPLE INC/SH SH",
  "cfiCode": "ESVUFR",
  "currency": "USD",
  "tradingVenue": "HAMB",
  "issuerLei": "HWUPKR0MPOU8FGXBT394",
  "maturityDate": null,
  "status": "ACTV",
  "ticker": "AAPL",
  "exchCode": "US",
  "securityType": "Common Stock",
  "marketSector": "Equity",
  "figi": "BBG000B9XRY4",
  "compositeFIGI": "BBG000B9XRY4"
}

Example Response — found via OpenFIGI only

{
  "valid": true,
  "issuerNumber": "037833",
  "issueNumber": "10",
  "checkDigit": "0",
  "isin": "US0378331005",
  "found": true,
  "dataSource": "openfigi",
  "name": "Apple Inc.",
  "fisn": null,
  "cfiCode": null,
  "currency": null,
  "tradingVenue": null,
  "issuerLei": null,
  "maturityDate": null,
  "status": null,
  "ticker": "AAPL",
  "exchCode": "US",
  "securityType": "Common Stock",
  "marketSector": "Equity",
  "figi": "BBG000B9XRY4",
  "compositeFIGI": "BBG000B9XRY4"
}

Example Response — not found

{
  "valid": true,
  "issuerNumber": "037833",
  "issueNumber": "10",
  "checkDigit": "0",
  "isin": "US0378331005",
  "found": false
}

Example Response — invalid

{
  "valid": false
}