parse-cusip

Validate and parse CUSIP identifiers (Committee on Uniform Securities Identification Procedures). Returns structured data: issuer, issue number, check digit, CINS detection, and security type classification.

Installation

npm install @credentum/parse-cusip

Usage

import { parseCUSIP } from '@credentum/parse-cusip';

const result = parseCUSIP('037833100');
// => {
//   raw: '037833100',
//   valid: true,
//   issuer: '037833',
//   issue: '10',
//   checkDigit: '0',
//   computedCheckDigit: '0',
//   isCINS: false,
//   isTreasury: false,
//   securityType: 'equity'
// }

Quick Validation

import { isValidCUSIP } from '@credentum/parse-cusip';

isValidCUSIP('037833100'); // true  (Apple)
isValidCUSIP('68389X106'); // false (bad check digit)

Compute a Check Digit

import { computeCheckDigit } from '@credentum/parse-cusip';

computeCheckDigit('03783310'); // '0' (Apple)
computeCheckDigit('17275R10'); // '2' (Cisco)

Why Use This?

Every fintech team working with US/Canadian securities encounters CUSIPs. The standard response is to copy-paste a gist or inline a validation function from Rosetta Code. There is no standalone, zero-dependency npm package that parses CUSIPs into structured data.

parse-cusip gives you:

• Validation via the ANSI X9.6 Modulus 10 Double Add Double algorithm
• Parsing that extracts issuer, issue number, check digit, and security type
• CINS detection (Committee on Uniform Security Identification Procedures International Numbering System — foreign securities)
• Treasury detection (US government securities starting with 9128/9127)
• Zero dependencies, pure TypeScript, <2KB

API

parseCUSIP(cusip: string): CUSIPResult

Parse a 9-character CUSIP string into structured data.

Parameters:

• cusip — A 9-character CUSIP string (digits, uppercase letters, *, @, #)

Returns: CUSIPResult

interface CUSIPResult {
  raw: string;              // Original input
  valid: boolean;           // Whether check digit is correct
  issuer: string;           // Characters 1-6 (issuer code)
  issue: string;            // Characters 7-8 (issue number)
  checkDigit: string;       // Character 9 (provided check digit)
  computedCheckDigit: string; // What the check digit should be
  isCINS: boolean;          // True if first character is a letter (foreign security)
  isTreasury: boolean;      // True if issuer starts with 9128 or 9127
  securityType: 'equity' | 'debt' | 'unit' | 'unknown';
}

isValidCUSIP(cusip: string): boolean

Returns true if the CUSIP has a valid format and correct check digit.

computeCheckDigit(cusip8: string): string

Compute the check digit for an 8-character CUSIP (without check digit). Returns a single digit character.

Test Vectors

| CUSIP | Company | Valid | |-------|---------|-------| | 037833100 | Apple Inc. | yes | | 17275R102 | Cisco Systems | yes | | 38259P508 | Google (Alphabet) | yes | | 594918104 | Microsoft | yes | | 68389X105 | Oracle | yes | | 68389X106 | Oracle (bad check) | no |

License

MIT