Security & API
JWT Debugger & Token Inspector
Decode, inspect, and analyze JSON Web Tokens in real time. Validate expiration countdowns, inspect registered claims, and format payloads with 100% private in-browser decoding.
100% Client-Side & Private: Token parsing runs entirely inside your browser JavaScript. Your keys, tokens, and payloads are never transmitted to any external server or saved to logs.
Sample Tokens:
Encoded Token
JWT Token Structure:
Header:Algorithm & token type
Payload:Claims, user data & expiry
Signature:Cryptographic verification
Token Lifecycle & StatusActive (in 1529 days)
Issued At (iat)
8/30/2024, 6:40:00 AM
Expires At (exp)
1/1/2031, 2:13:20 AM
Algorithm (alg)
HS256
Header: Algorithm & Token Type
{
"alg": "HS256",
"typ": "JWT"
}Payload: Data & Registered Claims
{
"sub": "user_123456",
"name": "Alex Chen",
"email": "alex@locionic.com",
"role": "admin",
"iat": 1725000000,
"exp": 1925000000
}Signature
dXBfaW5fdGhlX2Nsb3Vkc19zZWN1cmVfc2lnbmF0dXJl
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How to use
- 1Paste your raw encoded JWT string (e.g. eyJhbGciOi...) into the Encoded Token editor.
- 2Or click one of the preset sample tokens to see how active, expired, or role-based tokens are structured.
- 3Review the decoded Header, Payload claims, and Token Status badge on the right.
- 4Copy the beautified JSON with a single click to paste into Postman, curl, or your test suite.
Frequently asked questions
Is it safe to paste production JWTs into this debugger?
Yes, absolutely. Unlike many online decoders that send your token to an external server API for processing, this tool executes 100% locally in your browser memory using Web Crypto and Base64URL APIs. Your tokens, claims, and payload data never leave your computer.
What is a JSON Web Token (JWT)?
A JSON Web Token (RFC 7519) is a compact, URL-safe means of representing claims to be transferred between two parties. It consists of three parts separated by dots: a Header (signing algorithm and token type), a Payload (user data and registered claims), and a cryptographic Signature.
What do the standard claims (exp, iat, sub, iss) mean?
Standard JWT claims provide metadata about authentication: "sub" is the Subject (usually the unique user ID), "iss" is the Issuer (the authentication service that generated the token), "iat" is Issued At (Unix timestamp), and "exp" is Expiration Time (after which servers must reject the token).
Why does my application say "Token Expired"?
JWT expiration is enforced by the "exp" claim representing a Unix timestamp in seconds. When current server time exceeds the "exp" timestamp, backend libraries (like jose, jsonwebtoken, PyJWT) throw an expiration error. This tool displays the exact expiration timestamp and a relative countdown so you can easily verify whether a token is still valid.
Can this tool decode encrypted tokens (JWE)?
This tool decodes signed JSON Web Signatures (JWS), which are the standard format used by Auth0, Supabase, Firebase, NextAuth, and Clerk. Encrypted tokens (JWE) have five parts and encrypt their payload using a private key, meaning they cannot be inspected without the decryption key.
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