JWT Expiration Checker

Check JWT token

expiration

JWT Expiration Checker - Free Online JWT Token Expiration Checker

Free online JWT token expiration tool. Decode JWTand displays full information: exp (expiration time), iat (issued at), nbf (not before) in easy-to-read day hour format. Counts down the remaining time in realtime (day, hour, minute, second). Displays clear status: still valid (green) or expired (red). Copy JSON payload with one click. Handle 100% on browser - token don't sent to the server, ensuring security. Useful for developers when debugging authentication issues.

Outstanding features

Decode JWT tokenand display full payload
Check status: still valid (green) or expired (red)
Countdown of remaining time in realtime: days, hours, minutes, seconds
Display exp (expiration time) in local date and time format
Shows iat (issued at) - when the token was created
Displays nbf (not before) - when the token begins to take effect
Copy JSON payload with one click
Display header (algorithm, type)
Validate JWT format (3 parts separated by dots)
100% processed in the browser - token is not sent to the server
No token storage - safe with sensitive tokens
Supports all JWT algorithms: HS256, RS256, ES256...

What is JWT To and why is it necessary to check JWT expiration?

JWT (JSON Web Token) is open (RFC 7519) is widely used for authentication and authorization in web applications. JWT contains encoded and signed user information (claims), allowing the server to verify without querying the database. Most JWTs have an expiry date (exp claim) to increase security - if the token is leaked, it is only valid for a short time. When debugging authentication issues, the you often needs to know: Is the token still valid? hour expires? When is the token created? What does the payload contain? The JWT Expiration Checker tool helps you answer all these questions in seconds - just paste the token and see the results.

Benefits when used

  • •Debug authentication issues - identify expired tokens or other problems
  • •Troubleshoot 401 errors - check exp before looking for other causes
  • •Verify token refresh flow - ensures tokens are refreshed at the right time
  • •Audit security - check if token lifetime is appropriate
  • •Development testing - verify tokens during development
  • •API debugging - check tokens when testing API endpoints
  • •Learn JWT - see the JWT structure to understand how it works

How to use JWT Expiration Checker

  1. 1Copy JWT token from your application (DevTools browser, API response, logs...)
  2. 2Paste the token into the input box - the token has the format: xxxxx.yyyyy.zzzzz (3 parts separated by dots)
  3. 3Click the 'Check' button to decode and analyze the token
  4. 4View status: 'VALID' (green) or 'EXPIRED' (red) or 'NO EXP'
  5. 5See realtime countdown remaining time (if token is still valid)
  6. 6See details: Issued At (iat), Not Before (nbf), Expires At (exp)
  7. 7See the full payload in the right panel - contains all claims
  8. 8Click the Copy icon to copy the JSON payload if needed
  9. 9Repeat with other tokens for comparison

Frequently Asked Questions (FAQ)

What is JWT and how is it structured?

JWT (JSON Web Token) is an open standard (RFC 7519) for secure information transmission between parties. JWT consists of 3 parts separated by dots: Header (contains algorithm and type), Payload (contains claims/data), Signature (to verify the token has not been modified). Each part is Base64Url encoded. For example: eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiIxMjM0NTY3ODkwIn0.dozjgNryP4J3jVmNHl0w5N_XgL0n3I9PlFUP0THsR8U

What are exp, iat, nbf in JWT?

This is a registered claim in JWT: exp (expiration time) is the Unix timestamp when the token expires - after this time the token is no longer valid. iat (issued at) is the Unix timestamp when the token was created - useful for knowing how long the token has been around. nbf (not before) is the Unix timestamp when the token becomes valid - before this time the token is not valid. Not all JWTs have these 3 claims.

Is JWT secure? Can the payload be read?

JWT is signed so the payload cannot be modified without detection - the signature will be invalid. However, the payload is only Base64 encoded, NOT encrypted - anyone with the token can decode and read the payload. Therefore, sensitive information (passwords, credit cards) should NOT be stored in the JWT payload. Save only what is necessary: ​​user ID, roles, permissions.

What if the token expires? How to refresh it?

When the JWT expires (exp < current time), the server will refuse the request and return 401 Unauthorized. The client needs to get a new token in one way: Refresh token flow - use refresh token (with longer lifetime) to get a new access token. Re-authentication - ask the user to log in again. Silent refresh - automatically refresh before the token expires. Best practice is set short access token lifetime (15-60 minutes) and use refresh tokens.

What if the token does not have exp claim?

JWT does not require an exp claim - this is optional. Tokens without exp will never expire (from an exp perspective). However, this is bad security practice - if the token is leaked, the attacker can use it forever. Tool will display 'NO EXP' for this case. You should always set exp for production tokens.

Is the token sent to the server?

Don't. All processing (decode, parse, calculate time) takes place 100% in your browser using JavaScript. The token is not sent anywhere and is not stored. You can verify by opening the Network tab in DevTools - none of the requests contain tokens. Safe to use with production tokens.

Does the tool verify signature?

Don't. The tool only decodes and displays the payload, does not verify the signature. To verify signature, you need a secret key (HS256) or public key (RS256, ES256) - things you should not share. This tool focuses on checking expiration and viewing payload, not validating tokens. Your server will verify the signature when receiving the request.

Why is the displayed time different from expected?

Maybe due to timezone. exp, iat, nbf in JWT are Unix timestamp (UTC). Tool converts to the browser's local timezone for display. If the server and client are in different timezones, the displayed time will be different. Make sure to compare the correct timezone when debugging. Unix timestamp is always the source of truth.

Related keywords

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