Can I verify the signature?

Use the JWT Debugger for HS256 signature verification. This tool only decodes.

Why does the payload show future-dated fields?

JWTs commonly carry `exp`, `nbf`, and `iat` timestamps in seconds since epoch. The tool converts them to human-readable dates automatically.

JWT Decoder

Paste any JWT to see its header and payload as formatted JSON. The expiry is calculated and highlighted. Signature verification is not performed.

Runs locally in your browser

JWT token

0 chars · 1 line

JWT Debugger

Decode, verify, and edit JWTs with a signing secret.

Base64 Encode / Decode

Encode text or files to Base64 and decode them back.

Hash Generator

Compute MD5, SHA-1, SHA-256, and SHA-512 hashes.

HMAC Generator

Compute HMAC signatures with a shared secret.

About JWT Decoder

Paste any JWT to see its header and payload as formatted JSON. The expiry is calculated and highlighted. Signature verification is not performed.

JWT Decoder is part of FizzKit — a collection of focused, browser-based tools. Because everything runs locally, it works offline once loaded and never exposes your data to a remote server.

Frequently asked questions

No. Decoding happens entirely in your browser.

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