JWT Token Decoder

Paste any JSON Web Token to instantly decode and read its header algorithm, payload claims, expiration time, and issued-at fields without a secret key.

AUTH DEBUG

JWT Decoder

> Decode JWT header and payload locally in your browser.
> Inspect exp, iat, and nbf claims without sending bearer tokens to third-party sites.

JWT or Bearer token

Decode only

This tool decodes header and payload locally. It does not verify the signature or prove the token is trustworthy.

Header JSON

// Decoded JSON appears here...

Payload JSON

// Decoded JSON appears here...

Claim timing

Header, payload, signature segment state, and timestamp analysis will appear here.

Signature segment

// Signature segment appears here...

What this tool can and cannot tell you

Can decode header/payload structure locally.
Can show readable timestamps for exp, iat, and nbf.
Cannot verify the cryptographic signature.
Cannot prove the token was issued by the expected system.

What Does Decoding a JWT Reveal?

A JSON Web Token (JWT) is a compact, URL-safe string divided into three dot-separated parts: the header, payload, and signature. Decoding does not require the secret signing key — it simply base64url-decodes the first two segments to reveal the human-readable JSON inside. The header tells you the algorithm used to sign the token (e.g., HS256, RS256), and the payload contains all the claims: user ID, roles, expiration timestamp (exp), and any custom application data the token carries. Our decoder instantly reveals all these fields so you can debug authentication flows, inspect access tokens from OAuth providers, or audit security configurations without writing any code.

FAQ

Can I decode a JWT without the secret key?

Yes. Decoding simply converts the base64url-encoded segments back into readable JSON. The secret key is only needed to verify the cryptographic signature. Reading the payload data requires no secret whatsoever.

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Claim timing

Header, payload, signature segment state, and timestamp analysis will appear here.

Signature segment

// Signature segment appears here...

What this tool can and cannot tell you

Can decode header/payload structure locally.
Can show readable timestamps for exp, iat, and nbf.
Cannot verify the cryptographic signature.
Cannot prove the token was issued by the expected system.

What Does Decoding a JWT Reveal?