jwt-expiry

A lightweight utility to check if a JWT token has expired.

Installation

npm install jwt-expiry

Usage

import { isJwtExpired } from "jwt-expiry";

const token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...";

if (isJwtExpired(token)) {
  console.log("Token has expired");
} else {
  console.log("Token is still valid");
}

With Custom Skew

By default, the function considers a token expired 30 seconds before its actual expiration time (clock skew protection). You can customize this:

// Consider expired 60 seconds before actual expiration
isJwtExpired(token, 60);

// No skew - only expired if past actual exp time
isJwtExpired(token, 0);

API

isJwtExpired(token: string, skewSeconds?: number): boolean

| Parameter | Type | Default | Description | |-----------|------|---------|-------------| | token | string | - | JWT token string to check | | skewSeconds | number | 30 | Seconds before actual expiration to consider the token expired |

Returns: true if the token is expired or invalid, false if still valid.

Behavior

• Returns true if the token is malformed or cannot be decoded
• Returns true if the token has no exp claim
• Returns true if the token expires within the skew window
• Returns false if the token is valid and not expired

Types

import { JwtPayload } from "jwt-expiry";

// JwtPayload type
type JwtPayload = {
  exp: number;
  [key: string]: any;
};

License

MIT