How is the encoder different from the decoder?

The encoder builds a token from payload and secret; the decoder parses and verifies an existing token.

Is my secret sent to a server?

No. Encoding runs entirely in your browser.

Asymmetric signing needs a server private key; this tool supports HS256/384/512 for local debugging.

Create and sign JSON Web Tokens (JWT) with this online tool. Generate secure tokens with custom payloads.

Expires At

Part of tool topic

编码 JWT 后，您可能还需要验证或解码 JWT

JWT decode online—parse headers, payloads, and verify signatures

Generate secure random passwords, PINs, and Diceware passphrases

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Base64 encode and decode online with UTF-8 and visual breakdown

Team API management tool

Comprehensive symmetric encryption algorithms