Penglab JWT

JWT Decoder

Decode JWT header and payload claims instantly. This tool does not verify signatures.

JWT Token

Decoded Output

// Header and payload will appear here

Quick guide

What this tool does

Decode JWT header and payload segments in the browser so you can inspect claims without sending tokens to a server.

How to use it

Paste a JWT to decode the header and payload, inspect claims, and review token time fields without sending the token anywhere.

When this tool is useful

Inspect access-token claims during auth debugging without leaving the browser. Check exp, iat, and nbf timestamps quickly while investigating token issues. Review copied JWT payloads from logs or dashboards without verifying signatures elsewhere.

Common use cases

Inspect access-token claims during auth

Inspect access-token claims during auth debugging without leaving the browser.

Check exp

Check exp, iat, and nbf timestamps quickly while investigating token issues.

Review copied JWT payloads from

Review copied JWT payloads from logs or dashboards without verifying signatures elsewhere.

Example input and output

Example input

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjMiLCJyb2xlIjoiYWRtaW4iLCJleHAiOjE3NzM0NDkzMDF9.signature

Expected output

Header and payload are pretty-printed separately, with token time fields shown as ISO timestamps when available.

FAQ

Does this tool verify the JWT signature?

No. It decodes the header and payload for inspection only, which is useful for debugging but not for trust validation.

Does my token leave the browser?

No. The decoder runs locally in the browser, so copied tokens stay on your device unless you choose to share them.

Does JWT Decoder run in the browser?

Yes. JWT Decoder works in the browser so you can enter data, review the result, and copy the output without needing a separate desktop app.

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