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Free JWT Decoder — Decode JWT Tokens Online
Paste your JSON Web Token (JWT) to instantly decode its Header and Payload data. Runs entirely in your browser — your token never leaves your device.
When should you use this JWT Decoder & Validator?
- Inspect JWT header and payload contents instantly
- Debug authentication and authorization issues
- Verify token structure and expiration details
- When working with secure APIs and identity systems
Example use case:
You receive a JWT token from an authentication service and need to understand what data it contains. Paste the token into this tool to instantly decode the header and payload, inspect claims like issuer, expiration time, and user roles — all without sending the token to a server.
Tip: This tool decodes JWTs locally in your browser, so sensitive tokens never leave your device.
How to use the JWT Decoder
- 1
Paste the token
Paste the JWT (the part after “Bearer ”) into the Encoded JWT Token box. It is decoded automatically.
- 2
Read the header
The header shows the signing algorithm (alg, e.g. HS256 or RS256), the token type and sometimes a key id (kid).
- 3
Inspect the payload claims
Check exp (expiry), iat (issued at), iss (issuer), aud (audience), sub (user) and any custom claims like roles or scopes.
- 4
Convert timestamps
exp and iat are Unix timestamps in seconds. Paste them into the Epoch Converter to see the date and time.
Examples
Decoding a token
Token
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9 .eyJzdWIiOiIxIiwibmFtZSI6IkFkYSJ9 .isELjoOcNdKnCkXHJJBSZ4BNCo5SaLUptSrRhILmkHY
Decoded
Header: { "alg": "HS256", "typ": "JWT" }
Payload: { "sub": "1", "name": "Ada" }Common errors and how to fix them
This only supports JWT format (2 or 3 parts)- A JWT has three Base64URL parts separated by dots. Make sure you didn't copy the “Bearer ” prefix, quotes, or a truncated token.
Token decodes but the API returns 401- Decoding doesn't verify the signature. Check that exp is in the future, that iss and aud match what the API expects, and that it was signed with the right key.
Payload decoding failed- The token may be encrypted (a JWE has 5 parts) or not a JWT at all — some providers issue opaque access tokens that can't be decoded.
exp looks like a date far in the future- The value was set in milliseconds instead of seconds. JWT times must be in seconds since 1970.
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JWT Decoder FAQ
It decodes a JWT token to show the header and payload (claims) in readable JSON for debugging.
No. Decoding only reads the token content. Validity requires signature verification using the correct secret or public key.
If decoding is client-side, it stays in your browser. Still avoid pasting sensitive production tokens when possible.
Common claims include exp (expiry), iat (issued at), iss (issuer), aud (audience), and user role/permissions fields.
JWT uses Base64URL encoding to make token parts URL-safe by replacing certain characters and removing padding.
The token may be expired based on the exp claim. Also confirm timezone and server clock if results look wrong.