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Free JWT Decoder

Decode JWT tokens and inspect header, payload, and signature instantly.

About this tool

JSON Web Tokens (JWT) are a compact, URL-safe method of representing claims between two parties. A JWT consists of three Base64URL-encoded parts separated by dots: the Header (algorithm and token type), the Payload (claims - actual data), and the Signature (verification). This tool decodes the Header and Payload sections of any JWT, displaying them in a readable, formatted view. It also shows human-readable timestamps for standard claims like exp (expiration), iat (issued at), and nbf (not before), and alerts you if the token has expired. This tool is 100% client-side - your JWT never leaves your browser. This is critical because JWTs often contain sensitive user information and access tokens that could compromise security if exposed.

How to use

Step 1: Paste your JWT token into the input field above.
Step 2: Click Decode Token to inspect the Header and Payload sections.
Step 3: The Header section shows the algorithm (alg) and token type (typ).
Step 4: The Payload section shows all claims - user data, expiration time, and other metadata.
Step 5: Timestamp fields like exp and iat are automatically converted to human-readable dates.

Frequently Asked Questions

A JSON Web Token (JWT) is a compact, self-contained way to securely transmit information between parties as a JSON object. It is commonly used for authentication - after login, a server issues a JWT that the client sends with subsequent requests to prove its identity.

No. This tool only decodes the Header and Payload portions of a JWT. Verifying the signature requires the secret key (for HMAC algorithms) or the public key (for RSA/ECDSA), which you should never share with a browser tool. Signature verification should be done server-side.

Yes - this tool runs entirely in your browser. Your token never leaves your device and is never sent to any server. However, be cautious with production tokens in general - if exposed, they could grant unauthorized access until they expire.

The 'exp' (expiration time) claim identifies the time after which the JWT must not be accepted. It is a Unix timestamp (seconds since January 1, 1970). This tool automatically converts it to a readable date and warns you if the token has expired.

A JWT consists of: 1) Header - contains the token type (JWT) and signing algorithm (e.g., HS256, RS256). 2) Payload - contains the claims (statements about the user and metadata). 3) Signature - ensures the token was not tampered with.

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