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JWT Payload Inspector

Inspect JWT structure and claims without confusing decoding with verification.

This calculator runs in your browser. Nothing is sent to a server.

JWT

Three base64url segments. Never placed in the URL.

Mode

Verification is optional and local-only. Decoding is not trust.

HMAC key

Used only for local HS256 verification. Never persisted, shared, or logged.

Now (ISO or epoch seconds)

Empty uses the current device clock. Device clock is not an authority.

Display

Persist token (ignored)Persist token (ignored)

Secrets and tokens are never persisted even if this is turned on.

How it works

Processing stays in this browser tab. Source files are not uploaded. Export is a new copy; originals are not overwritten.