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FizzKit

JWT Debugger

Full JWT toolkit: decode tokens, verify HS256/HS384/HS512 signatures with a shared secret, and re-encode with edited claims. Asymmetric algorithms are decoded but not verified.

Runs locally in your browser
JWT token
0 chars · 1 line
Paste a JWT above to see verification details.

Related tools

JWT Decoder

Decode and inspect JWT header and payload.

HMAC Generator

Compute HMAC signatures with a shared secret.

Hash Generator

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

Bcrypt Generator / Checker

Hash passwords with bcrypt and verify existing hashes.

About JWT Debugger

Full JWT toolkit: decode tokens, verify HS256/HS384/HS512 signatures with a shared secret, and re-encode with edited claims. Asymmetric algorithms are decoded but not verified.

JWT Debugger 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

HS256, HS384, and HS512 (HMAC-SHA). RS and ES algorithms are decoded but not verified client-side.