JWT Decoder & Inspector
Paste a JWT token to decode and inspect its header, payload, and claims. Instantly see token expiration status and all standard JWT properties. All processing happens in your browser.
Header
Payload
Standard Claims
Issuer
Not present
Subject
Not present
Audience
Not present
Expiration Time
Not present
Not Before
Not present
Issued At
Not present
JWT ID
Not present
Signature
-
What is a JWT token?
JSON Web Token (JWT) is a compact, URL-safe standard for representing claims between two parties. JWTs are commonly used for authentication and information exchange in web applications and APIs.
A JWT consists of three Base64URL-encoded parts separated by dots: the header (algorithm and token type), the payload (claims and user data), and the signature (verification hash). This tool decodes the first two parts to show you the token's contents.
JWT Structure
- Header: Contains algorithm (alg) and token type (typ)
- Payload: Contains claims like user ID, expiration, issuer, etc.
- Signature: Cryptographic verification using the header's algorithm
Common use cases
- Debug authentication flows in web applications
- Inspect API tokens during development
- Validate token claims and expiration times
Features
- Instant header and payload decoding
- Automatic expiration checking
- Pretty-printed JSON with syntax highlighting
FAQs
What is a JWT token?
JSON Web Token (JWT) is a stateless authentication standard that encodes claims in three Base64URL-encoded parts: header, payload, and signature. It's widely used for secure information exchange.
Is it safe to decode JWTs here?
Yes. All decoding happens locally in your browser using JavaScript. No token data is ever sent to any server, ensuring your sensitive information stays private.
Can this tool verify JWT signatures?
This tool decodes and displays the JWT contents but does not verify signatures, as that requires the secret key (HS256) or public key (RS256). Use this for inspection only.
Why are there three parts in a JWT?
The three parts are: header (metadata), payload (claims/data), and signature (verification). They're separated by dots and each part is independently Base64URL-encoded.
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