JWT Expiry Checker & TTL Duration Countdown

What does the JWT Expiry Checker & TTL Duration Countdown do?

The JWT Expiry Checker & TTL Countdown decodes JSON Web Tokens (JWT) client-side to evaluate security timeframe claims (exp, iat, nbf). It calculates the remaining validity duration (Time-To-Live), runs an active real-time countdown timer, displays visual lifespan timeline progress bars, and detects clock skew desynchronization issues.

Core Concepts

Understanding JWT expiration and lifecycle claims:

• Expiration Time (exp): The epoch timestamp (in seconds) after which the token must not be accepted for authentication.
• Issued At (iat) & Not Before (nbf): Define the token's creation timestamp and earliest allowable usage threshold.
• Time-To-Live (TTL): The dynamic remaining lifespan (exp - currentTime) indicating seconds left before session expiration.
• Clock Skew Detection: Identifies whether tokens were issued in the future relative to the client clock, signaling server NTP desynchronization.

How to use the tool?

1. Enter JWT: Paste your encoded Header.Payload.Signature JWT token into the text area or click Load Sample Token.
2. Execute Analysis: Click Analyze Token Validity to decode payload claims and calculate lifespan metrics.
3. Inspect Claims: Review the live countdown status, timeframe parameters (iat, nbf, exp), timeline progress bar, and raw payload JSON.

Related Developer Utilities

If you work with JWT authentication, Base64 encodings, and web security tokens, explore these complementary tools:

• JWT Token Decoder: Decode and format JWT header and payload claims into JSON.
• Base64URL to Base64 Converter: Convert URL-safe Base64 strings to standard Base64.
• Base64 to Base64URL Converter: Convert standard Base64 payloads into URL-safe strings.
• JSON Syntax Validator: Validate and inspect JSON payload structures.

REST API Integration

Blueutils provides a free REST API endpoint (POST https://blueutils.com/api/jwt/jwt-expiry-checker) to programmatically decode JSON Web Tokens and extract expiration timestamps.

API Request Parameters

API Request Payload Examples

cURL

curl -X POST https://blueutils.com/api/jwt/jwt-expiry-checker \
  -H "Content-Type: application/json" \
  -d '{
    "rawToken": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiZXhwIjoxNzczNjYzMDAwfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c"
  }'

Python

import requests

url = "https://blueutils.com/api/jwt/jwt-expiry-checker"
payload = {
    "rawToken": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiZXhwIjoxNzczNjYzMDAwfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c"
}
headers = {"Content-Type": "application/json"}
response = requests.post(url, json=payload, headers=headers)
print(response.json())

Java

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

public class Main {
    public static void main(String[] args) throws Exception {
        String jsonPayload = """
            {
                "rawToken": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiZXhwIjoxNzczNjYzMDAwfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c"
            }
            """;

        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create("https://blueutils.com/api/jwt/jwt-expiry-checker"))
            .header("Content-Type", "application/json")
            .POST(HttpRequest.BodyPublishers.ofString(jsonPayload))
            .build();

        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
        System.out.println(response.body());
    }
}

API Response Parameters

API Response Payload Examples

Success Response (HTTP 200 OK)

{
  "isValid": true,
  "exp": 1773663000,
  "iat": 1773659400,
  "nbf": null,
  "nowSeconds": 1773659400,
  "isExpired": false,
  "isNotYetValid": false,
  "isClockSkewed": false,
  "totalDuration": 3600,
  "elapsedDuration": 0,
  "remainingDuration": 3600,
  "payload": {
    "sub": "1234567890",
    "name": "John Doe",
    "exp": 1773663000
  }
}

Validation Failure Response (HTTP 400 Bad Request)

{
  "isValid": false,
  "error": "Target token does not contain an \"exp\" (Expiration Time) claim payload."
}

Rate Limit Exceeded Response (HTTP 429 Too Many Requests)

{
  "error": "API rate limit exceeded. Please wait or contact support@blueutils.com."
}

Why use an API to check JWT expiration?

Integrating the JWT Expiry Checker API into gateway routers, test automation scripts, or AI agent tool calling provides key benefits:

• Rapid Script Validation: Verifies bearer token lifespans before dispatching API calls to prevent avoidable 401 Unauthorized errors.
• Optimized Token Efficiency for AI Agents: LLMs frequently miscalculate Unix epoch durations and relative seconds. Calling the API computes remaining TTL and clock skew deterministically without token consumption.
• Deterministic Accuracy Without Hallucinations: Ensures 100% accurate Base64URL decoding and epoch timestamp comparison.

Native Usage

How to inspect JWT expiration locally in terminal environments or scripts:

Windows (CMD / PowerShell)

# Decode JWT payload and check exp in PowerShell
$token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwiZXhwIjoxNzczNjYzMDAwfQ.sig"
$parts = $token.Split('.')
$base64 = $parts[1].Replace('-', '+').Replace('_', '/')
$base64 = $base64.PadRight($base64.Length + (4 - $base64.Length % 4) % 4, '=')
$json = [System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String($base64))
$payload = ConvertFrom-Json $json
Write-Output "Expires at epoch: $($payload.exp)"

Linux / Unix (Bash)

# Decode JWT payload and check exp using jq in Linux
token="eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwiZXhwIjoxNzczNjYzMDAwfQ.sig"
echo "$token" | cut -d'.' -f2 | base64 -d 2>/dev/null | jq .exp

Python

Using Python:

import base64
import json
import time

token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwiZXhwIjoxNzczNjYzMDAwfQ.sig"
payload_b64 = token.split('.')[1]
payload_b64 += '=' * (-len(payload_b64) % 4)
payload = json.loads(base64.urlsafe_b64decode(payload_b64))

remaining = payload['exp'] - int(time.time())
print(f"Token expires in {remaining} seconds.")

Java

Using Java:

import java.util.Base64;

public class JwtExpiryExample {
    public static void main(String[] args) {
        String token = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwiZXhwIjoxNzczNjYzMDAwfQ.sig";
        String payloadJson = new String(Base64.getUrlDecoder().decode(token.split("\\.")[1]));
        System.out.println("Payload: " + payloadJson);
    }
}