JWT Token Decoder & Expiration Inspector
Decode and inspect JSON Web Tokens (JWT) client-side in real time. Inspect header algorithms, claims, payload data, expiration dates.
JWT Token Decoder & Expiration Inspector
Parse, inspect, and validate JSON Web Tokens in real time with 100% client-side privacy. No tokens are sent over the network.
Header (Algorithm & Type)
{
"alg": "HS256",
"typ": "JWT"
}Standard Claims Analysis
Payload (Claims & Data)
{
"sub": "usr_98421b8c",
"name": "Alex Mercer",
"role": "admin",
"iss": "https://auth.toolsfor.co",
"aud": "https://api.toolsfor.co",
"iat": 1700000000,
"exp": 1800000000
}Signature
signature_sample_only_hs256_mock
HMAC-SHA256 signature verified against public header specifications.
About this tool
How to use it
- Paste any valid Base64Url-encoded JSON Web Token (JWT) into the input box.
- The decoder automatically splits the token into Header, Payload, and Signature segments.
- Inspect claims like exp, iat, sub, iss, and aud with real-time expiration countdown calculations.
- Copy formatted JSON payloads or headers with a single click.
Why it matters
Many online JWT tools transmit raw tokens across remote servers, risking exposure of sensitive API keys, user IDs, or company secrets. This tool executes 100% locally in your browser memory using native Web APIs, ensuring absolute confidentiality while diagnosing authentication bugs.
When to use it
Use this tool when debugging API authorization headers (Bearer tokens), verifying OAuth2 and OpenID Connect ID tokens issued by Cognito, Auth0, Okta, or Supabase, or auditing embedded scopes and user roles.
Common questions
Are my tokens sent to any server?
No. All decoding and timestamp parsing happens strictly inside your browser client memory. No telemetry or token data is transmitted over the network.
What does an exp timestamp mean?
The exp (Expiration Time) claim identifies the exact Unix timestamp after which the JWT must not be accepted for processing by servers or APIs.
Can I verify the token signature without exposing my private key?
Yes. While this tool parses the signature segment visually, standard client-side debugging should never require pasting private keys into web browsers.
Does this tool support nested or encrypted tokens (JWE)?
This tool specializes in standard JSON Web Signatures (JWS). Encrypted JWE tokens require key decryption prior to inspecting claims.