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JWT Decoder Online Privately
Decode JSON Web Tokens instantly to inspect header claims, payload parameters, and expiration timestamps with zero network transmission.
JWT Decoder
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Why Cloud JWT Decoders Are a Severe Security Risk
JSON Web Tokens (JWTs) often contain sensitive user IDs, role permissions, email addresses, and session tokens. If you paste a production JWT into a remote online decoder, your tokens could be logged and exploited for session hijacking.
ToolMint decodes the Base64URL-encoded Header and Payload segments 100% locally in your web browser using the Web Crypto and Base64 APIs. Your token never leaves your machine.
JWT Structure Breakdown
- Header: Specifies the cryptographic algorithm (e.g. HS256, RS256) and token type.
- Payload: Contains claims such as subject (
sub), issuer (iss), and expiration (exp). - Signature: The cryptographic checksum ensuring token authenticity.
Frequently Asked Questions
Can ToolMint verify the signature of my JWT?
ToolMint parses and decodes the token claims client-side. To verify HMAC or RSA signatures locally, you can supply your public key without sending it to any server.
What does the exp claim in a JWT represent?
The 'exp' (expiration time) claim represents the UNIX timestamp in seconds after which the token is invalid. ToolMint automatically translates this timestamp into a human-readable date.