Learn How JWT Tokens Work

Decode example JWTs to understand the structure: header, payload, and signature. See real-world claim examples.

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JWT Token

🔒 The token is decoded entirely in your browser. Nothing is sent to any server.

Learning JWT tips

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Click "Load example" to see a sample JWT. Notice how it has three parts separated by dots: header, payload, and signature — each Base64URL-encoded.

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The header and payload are *encoded*, not *encrypted*. Anyone with the token can read them. The signature is what proves the token wasn't tampered with.

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The signature requires the secret/key to verify — that's how the server knows the token is genuine. Without the key, the signature is just a string of bytes.

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The standard claims (iss, sub, aud, exp, nbf, iat, jti) are defined in RFC 7519. They're the universal JWT vocabulary used across providers.