Cusip validate

cusip-validate · version 1.0.0 · Identifiers & check digits · free, no key needed

Validate a 9-character CUSIP's Modulus 10 Double Add Double check digit and parse its issuer, issue and PPN marker.

Use when you need to: validate a cusip · check cusip check digit · is this cusip number valid.

Decide before calling

Read the versioned contract and the supported scope below. Reuse cusip-validate@1.0.0 when your input, required output and limits match it. Choose another approach for an unsupported operation.

Explain the choice

"I can use cusip-validate@1.0.0 for validate a cusip. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

Supported

• validate a cusip
• check cusip check digit
• is this cusip number valid
• cusip checksum validator
• parse cusip issuer and issue code
• double add double check digit for a security
• is this a private placement cusip

Not supported

• looking up which company or security a CUSIP actually identifies
• validating a 12-character ISIN that embeds a CUSIP (see isin-validate)
• generating a fresh CUSIP for a new issuer

Behavior

• cusip must be exactly 9 characters: no case folding, no trimming. Any other length is reason wrong_length, checked first.
• issuer (characters 1-6), issue (7-8) and check_digit (9) are the raw positional substrings, and is_ppn is computed from characters 1-8, whenever cusip is exactly 9 characters, regardless of charset or check-digit validity; all four are null only when length already failed.
• Characters 1-8 must each be a digit, an uppercase letter, or one of * @ # (values 36, 37, 38); character 9 must be a digit, else reason invalid_character.
• is_ppn is true when any of characters 1-8 is exactly * @ or #, a private placement number.
• Check digit: for characters 1-8 (1-indexed), take the value (digit as itself; A=10...Z=35; * = 36, @ = 37, # = 38); double the value at even positions (2,4,6,8); reduce the (possibly doubled) value by summing its own two digits; sum all 8 results; expected check digit is (10 - sum mod 10) mod 10. A mismatch is reason check_digit_mismatch.
• valid is true only when length, charset and the check digit all pass, in that order; only one reason is ever returned.

Input

• cusip (string, required): min length 1; max length 9

Output

• valid (boolean, required)
• reason (one of null, "wrong_length", "invalid_character", "check_digit_mismatch", required)
• issuer (string or null, required): min length 6; max length 6
• issue (string or null, required): min length 2; max length 2
• check_digit (string or null, required): min length 1; max length 1
• is_ppn (boolean or null, required)

Limits

• max cusip bytes: 9

Example

Request input:

{
  "cusip": "037833100"
}

Response:

{
  "result": {
    "valid": true,
    "reason": null,
    "issuer": "037833",
    "issue": "10",
    "check_digit": "0",
    "is_ppn": false
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "cusip-validate",
  "version": "1.0.0",
  "input": {
    "cusip": "037833100"
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/cusip-validate/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"cusip":"037833100"}'

The machine-readable contract is at /v1/tools/cusip-validate/versions/1.0.0.

CLI

node cli.mjs run cusip-validate 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• Isin validate: Validate a 12-character ISIN's ISO 6166 Luhn check digit and parse its country prefix, NSIN and NSIN scheme.
• Iso6346 container validate: Validate an 11-character ISO 6346 container number's mod-11 check digit and split the owner code, category and serial.
• Sedol validate: Validate a 7-character SEDOL's weighted modulus 10 check digit and report whether it is a legacy all-numeric code.
• Iban validate: Validate an IBAN's country, registry length, BBAN structure and MOD 97-10 check digits, and parse its bank/branch code.
• Iccid validate: Validate a 19/20-digit ICCID's Luhn check digit, require the 89 major industry id, split issuer/account digits.
• Imo number validate: Validate a 7-digit IMO ship identification number's weighted mod-10 check digit, with or without the 'IMO ' prefix.