Securities identifier math in one package — CUSIP, ISIN, SEDOL, FIGI, and LEI: validation, parsing, check-digit computation, and CUSIP→ISIN / SEDOL→ISIN conversion. Zero dependencies.
npm install instrument-identifiers
Every trading, settlement, or reference-data system juggles at least three identifier schemes, and each has its own check-digit algorithm (CUSIP's mod-10 double-add-double, ISIN's ISO 6166 Luhn, SEDOL's 1-3-1-7-3-9 weights, FIGI's OMG spec, LEI's ISO 7064 MOD 97-10). npm had them scattered across single-purpose validators — several dead, none doing conversion. This package is the whole set, strictly the free algorithm layer: no licensed identifier database content.
import { isValidCusip, cusipToIsin, parseIsin, identify } from "instrument-identifiers";
isValidCusip("91282CQQ7"); // true — a live Treasury note
cusipToIsin("037833100"); // "US0378331005" — Apple, real ISIN reproduced
parseIsin("US0378331005"); // { countryCode: "US", nsin: "037833100", checkDigit: 5 }
identify("BBG000B9XRY4"); // ["FIGI"]Per identifier — isValidX(value), xCheckDigit(base), and where the structure is meaningful, parseX(value):
| Identifier | Validate | Check digit | Parse | Convert |
|---|---|---|---|---|
| CUSIP (9) | isValidCusip |
cusipCheckDigit(base8) |
parseCusip → issuer/issue |
cusipToIsin(cusip, cc?) |
| ISIN (12) | isValidIsin |
isinCheckDigit(payload11) |
parseIsin → country/NSIN |
— |
| SEDOL (7) | isValidSedol |
sedolCheckDigit(base6) |
— | sedolToIsin(sedol, cc?) |
| FIGI (12) | isValidFigi |
figiCheckDigit(base11) |
parseFigi → prefix/id |
— |
| LEI (20) | isValidLei |
leiCheckDigits(base18) |
— | — |
Plus identify(value) → every type the value validly matches. Inputs are case-insensitive; validators return booleans, everything else throws RangeError on malformed input. Format rules are enforced (FIGI's mandatory G, excluded country-like prefixes, SEDOL's no-vowels alphabet).
- Real-world anchors: Apple's CUSIP/ISIN/FIGI/LEI, a live US Treasury CUSIP, BAE's SEDOL→ISIN — each reproduced, not just validated.
- Cross-checked against an independent Python reference implementation (
test/generate-fixtures.py): 300+ generated identifiers per run, every one validated and its check digit recomputed, plus corruption tests (every fixture with a damaged check digit must fail).
Part of a small fixed-income toolkit: 32nds · day-count · accrued-interest · sifma-holidays · treasurydirect · tbill · newyorkfed.
Built by Moshe Malka — engineering leader in New York City. Studio work at Quentin.Code.
MIT © Moshe Malka