US ACH/ABA Routing Number Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching us ach/aba routing 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

// US ACH/ABA Routing Number
// ReDoS-safe | RegexVault — Finance > Bank Identifiers

const usAchabaRoutingNumberRegex = /^(?:0[1-9]|1[0-2]|2[1-9]|3[0-2]|6[1-9]|7[0-2]|80)[0-9]{2}(?!0{5})[0-9]{5}$/;

function validateUsAchabaRoutingNumber(input: string): boolean {
  return usAchabaRoutingNumberRegex.test(input);
}

// Example
console.log(validateUsAchabaRoutingNumber("021000021")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Finance > Bank Identifiers 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

The first two digits identify the Federal Reserve District (01-12), Federal Home Loan Bank (21-32), or special assignment (61-72, 80). Checksum: (3*(d1+d4+d7) + 7*(d2+d5+d8) + (d3+d6+d9)) mod 10 = 0.