ISIN (International Securities Identification Number) Regex for PHP
/^(?!XX)[A-Z]{2}[A-Z0-9]{9}[0-9]$/What this pattern does
This page provides a comprehensive, battle-tested regular expression for matching isin (international securities identification number), ported and verified for PHP. Financial data validation has zero tolerance for false negatives — a missed invalid entry can corrupt downstream calculations. The snippet below is ready to drop into your PHP project — whether you're validating in a Laravel validator, a WordPress plugin, or a standalone PHP script.
Php Implementation
<?php
// ISIN (International Securities Identification Number)
// ReDoS-safe | RegexVault — Finance > Securities & Trading
define('ISIN_INTERNATIONAL_SECURITIES_IDENTIFICATION_NUMBER_PATTERN', '/^(?!XX)[A-Z]{2}[A-Z0-9]{9}[0-9]$/');
function validate_isin_international_securities_identification_number(string $input): bool {
return (bool) preg_match(ISIN_INTERNATIONAL_SECURITIES_IDENTIFICATION_NUMBER_PATTERN, $input);
}
// Example
var_dump(validate_isin_international_securities_identification_number("US0378331005")); // bool(true)Test Cases
Matches (Valid) | Rejects (Invalid) |
|---|---|
US0378331005 | US03783310051 |
GB0002634946 | US037833100 |
JP3633400001 | us0378331005 |
DE0005140008 | US0378331005A |
AU000000CBA7 | XX0378331005 |
When to use this pattern
This pattern is drawn from the Finance > Securities & Trading category and carries a ReDoS-safe certification. That matters for PHP developers because especially relevant in PHP where PCRE backtracking limits can trigger silent failures on malicious input. 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
Always validate the Luhn check digit — a structurally valid ISIN with an invalid check digit is not a valid ISIN. Use country code XS for Eurobonds, US for SEC-registered securities.
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.
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