JWT Decoder

Decode JWT (JSON Web Token) into Header, Payload, and Signature to instantly inspect the contents

JWT Token Input

Paste a JWT in the standard 3-part format separated by dots (.) for instant decoding.

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Use Cases

Auth Token Inspection

Paste an Access Token from an API response to instantly inspect the user ID, roles, expiration time (exp), and other payload claims.

Development Debugging

Quickly verify that a JWT issued by your backend contains the correct claims and that the algorithm is configured as expected.

API Testing

Copy a JWT from a Postman or curl response and paste it here to understand the exact claim structure returned by the server.

Token Expiry Check

Automatically converts exp, iat, and nbf Unix timestamps to human-readable dates so you can easily check token validity periods.

Pro Tips

Quick Paste

Click the 'Paste' button at the top or use Ctrl+V directly in the textarea to instantly paste your JWT from the clipboard.

Real-Time Decoding

Decoding happens instantly as you type or paste. No need to click any button — the result appears the moment you paste the token.

Automatic Timestamp Parsing

If the payload contains exp, iat, or nbf claims, their Unix timestamps are automatically converted to human-readable date/time format.

Security Note

This tool runs entirely in your browser. Your token is never sent to any server, making it safe to use with sensitive tokens.

FAQ

Can this tool verify the JWT signature?
No. This tool is for decoding purposes only and does not support signature verification. To verify a signature, you need the secret key on the server side.
Is my JWT token sent to a server?
No. All decoding is performed entirely in your browser. Nothing is transmitted to any server, so sensitive tokens are safe to use here.
Does it support tokens with non-ASCII characters (e.g., Korean)?
Yes. The decoder correctly handles UTF-8 multi-byte encoding, so all Unicode characters including Korean and other languages are displayed correctly without corruption.
Why do I see 'Invalid JWT format'?
A valid JWT must consist of exactly 3 parts separated by dots (Header.Payload.Signature). This error appears if the token was copied incompletely or contains extra whitespace.
JWT Decoder | DDTool