JWT (JSON Web Token) Decoder
Safely decode and inspect JSON Web Tokens without ever exposing sensitive authentication tokens to remote servers.
Security Notice: Tokens are parsed purely client-side via JavaScript. No tokens, secrets, or payloads are ever sent across the network.
How to Use JWT Decoder
- Paste your encoded JWT into the token input box.
- Inspect the automatically decoded Header and Payload JSON structures.
- Review the token expiration status, algorithm, and validity indicator.
- Copy claims or clear the token with a single click.
Technical Specifications & How It Works
JSON Web Tokens (JWTs) are an open industry standard (RFC 7519) for securely transmitting information between parties as a compact JSON object.
Many online JWT decoders transmit tokens to backend servers, creating severe security risks if the token contains sensitive bearer credentials or API keys.
Toolswick decodes base64url segments strictly inside your browser sandbox, guaranteeing that credentials never leave your device.
Frequently Asked Questions
Is my token transmitted or logged anywhere?
No. Decoding runs 100% locally in your browser memory. No tokens or payloads are ever sent across the network.
Does this tool verify token signatures?
This tool focuses on client-side decoding and expiration inspection. Verifying signatures requires your private key or shared secret, which should never be entered into any web tool.
What do the three parts of a JWT represent?
A JWT consists of Header (algorithm & token type), Payload (claims like user ID, roles, and exp), and Signature (verifies integrity).