ISIN (International Securities Identification Number) Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching isin (international securities identification number), ported and verified for JavaScript. Financial data validation has zero tolerance for false negatives — a missed invalid entry can corrupt downstream calculations. The snippet below is ready to drop into your JavaScript project — whether you're validating in an Express middleware, a Next.js API route, or a client-side form.

Javascript Implementation

// ISIN (International Securities Identification Number)
// ReDoS-safe | RegexVault — Finance > Securities & Trading

const isinInternationalSecuritiesIdentificationNumberRegex = /^(?!XX)[A-Z]{2}[A-Z0-9]{9}[0-9]$/;

function validateIsinInternationalSecuritiesIdentificationNumber(input: string): boolean {
  return isinInternationalSecuritiesIdentificationNumberRegex.test(input);
}

// Example
console.log(validateIsinInternationalSecuritiesIdentificationNumber("US0378331005")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Finance > Securities & Trading category and carries a ReDoS-safe certification. That matters for JavaScript developers because especially critical in long-running Node.js event loops where a ReDoS vulnerability can block the entire process. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

ISIN structure: 2-char ISO 3166-1 country code + 9-char NSIN (National Securities Identifying Number, right-padded with zeros) + 1 Luhn check digit. US ISINs use CUSIP as the NSIN.