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Simple Toolkit

Client-Side JWT Validator & Generator

Decode, validate, and generate JSON Web Tokens locally in your browser. Zero uploads — your secret keys and private keys never leave your device.

Client-Side JWT Validator & Generator

Zero Uploads, 100% Client-Side Cryptography — your keys never leave your browser.

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FAQ — Trust & Security

Does my Secret Key leave my browser? No. All cryptographic operations use the Web Crypto API and keys are imported locally — nothing is uploaded.

Which algorithms are supported? This UI supports HS256 for generation and validation. RS256 verification is supported when you paste a public key PEM (verification only).

Can I verify tokens signed elsewhere? Yes — paste the token and provide the matching secret (HS256) or public key PEM (RS256).

Zero Uploads — Keys Stay Local

All cryptographic operations use the browser Web Crypto API (SubtleCrypto). Secrets and private keys are imported and used only in-memory; nothing is sent to external servers.

Frequently Asked Questions

Does my Secret Key leave my browser?
No. Keys are imported into the browser's SubtleCrypto and used in-memory. Nothing is transmitted or stored externally by this app.
Which algorithms are supported?
This UI supports HS256 generation and validation, and RS256 verification when you provide a public key PEM. RS256 signing (private key generation) is intentionally not provided to avoid exposing private keys in the browser.
Can I verify tokens created elsewhere?
Yes. Paste the token and provide the correct shared secret (for HS256) or public key PEM (for RS256) to verify signatures locally.

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