Generic Bearer Token (Authorization Header) Regex for JavaScript

What this pattern does

This page provides a well-structured, multi-part regular expression for matching generic bearer token (authorization header), ported and verified for JavaScript. In security-sensitive code, using an unverified regex can open the door to both false positives and denial-of-service attacks. 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

// Generic Bearer Token (Authorization Header)
// ReDoS-safe | RegexVault — Security > API Keys & Tokens

const genericBearerTokenAuthorizationHeaderRegex = /^Bearer\s+([A-Za-z0-9\-._~+\/]+=*)$/i;

function validateGenericBearerTokenAuthorizationHeader(input: string): boolean {
  return genericBearerTokenAuthorizationHeaderRegex.test(input);
}

// Example
console.log(validateGenericBearerTokenAuthorizationHeader("Bearer eyJhbGciOiJSUzI1NiJ9.abc.def")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Security > API Keys & Tokens 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

RFC 6750 Bearer token format. The token itself is an opaque string — not validated structurally here. The character set covers base64url, standard base64, and common token formats. Use downstream pattern to validate the token type (JWT, opaque, etc.).