Decode JSON Web Tokens instantly. Nothing is sent to any server.
Paste JWT. See header, payload, signature. Timestamps become human-readable. Copy details.
Debugging auth issues requires JWT inspection. Decode instantly without terminal.
Compact URL-safe token representing claims; common for auth.
Yes, local decoding only.
Shows signature; cannot verify without key.
iss (issuer), exp, sub, aud, iat common.
JWT (JSON Web Token) is a compact, URL-safe format for transmitting claims between parties. A JWT has three parts separated by dots: header.payload.signature. The header describes the token type and signing algorithm. The payload contains the claims (user ID, expiry, permissions). The signature verifies the token hasn't been tampered with. JWTs are commonly used for authentication: after login, the server returns a JWT, and the client sends it on subsequent requests to prove identity.
Traditional session auth stores user state on the server. JWT is stateless: all user info is in the token itself. Pros of JWT: scales horizontally (no shared session store needed), works across domains (cookies don't), mobile-friendly. Cons of JWT: can't be revoked before expiry (you need a blocklist), larger request size (sent on every request), and storing sensitive data in the payload is a security risk (payload is just Base64-encoded, not encrypted).
This decoder runs entirely in your browser. Your JWT is never sent to any server. However, never paste JWTs from production systems into any online tool unless you trust the operator — JWTs often contain session credentials that attackers can use to impersonate users. Even with browser-based tools, only use them on test tokens. For real debugging, use your team's internal tools.
Decode and inspect JSON Web Tokens (JWTs) instantly with the Toolzie JWT Decoder. See the header, payload, and signature of any JWT — useful for debugging authentication flows in web applications.
JWTs are decoded locally in your browser — they are not sent to any server. However, avoid pasting production tokens from sensitive systems as a general security practice.
Signature verification requires the secret key. This tool decodes the payload without verifying the signature.
JWTs are used to securely transmit authentication and authorization claims between a client and server in web applications.
The exp claim is a Unix timestamp indicating when the token expires. This tool shows the human-readable expiry time.