Browser Fingerprint Hash Regex for JavaScript

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching browser fingerprint hash, ported and verified for JavaScript. Identity and credential patterns need both correctness and safety, since they're frequent targets for adversarial input. 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

// Browser Fingerprint Hash
// ReDoS-safe | RegexVault — Identity & PII > Digital Identity

const browserFingerprintHashRegex = /^[0-9a-f]{32}$|^[0-9a-f]{64}$/i;

function validateBrowserFingerprintHash(input: string): boolean {
  return browserFingerprintHashRegex.test(input);
}

// Example
console.log(validateBrowserFingerprintHash("d41d8cd98f00b204e9800998ecf8427e")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Identity & PII > Digital Identity 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

Browser fingerprinting combines canvas, WebGL, fonts, plugins, and device characteristics into a hash. Under GDPR recital 30, fingerprinting constitutes tracking. Under ePrivacy Directive, it requires consent. 32 chars = MD5, 64 chars = SHA-256.