Encode / Decode

JWT Debugger

Paste a JWT and instantly see the decoded header and payload with all claims rendered as human-readable text. Timestamps (exp, iat, nbf) are converted to ISO dates. You can verify the signature using an HMAC secret or an RSA/ECDSA public key, and you can sign new tokens with your own payload and secret.

JWT Debugger — Decode JWT tokens, inspect claims, verify signatures, and sign new tokens

What it does

  • ▸Decodes JWT header and payload, showing all claims in readable form
  • ▸Converts epoch timestamps (exp, iat, nbf) to human-readable ISO dates
  • ▸Verifies HMAC signatures (HS256, HS384, HS512) with a secret
  • ▸Verifies RSA and ECDSA signatures (RS256, ES256, etc.) with a public key
  • ▸Signs new JWT tokens with a custom payload and secret/key
  • ▸Handles clock tolerance for tokens near expiration

Use cases

  • ▸Debugging an auth issue by inspecting the claims in a JWT from your API
  • ▸Verifying a token's signature to confirm it wasn't tampered with
  • ▸Creating a test token with custom claims for API testing
  • ▸Checking if a token has expired or will expire soon

How it works

1

Paste your JWT into the input pane (or use Auto mode to detect it from clipboard)

2

The header and payload are decoded and displayed as formatted JSON

3

Enter an HMAC secret or paste a public key to verify the signature

4

To sign a new token, switch to sign mode, enter your payload JSON and secret

Frequently asked questions

1Can it verify tokens signed with RS256 or ES256?

Yes. Paste the PEM-encoded public key (SPKI format) into the public key field. The tool uses the jose library to import the key and verify the signature with the algorithm specified in the token header.

2Does it work with refresh tokens and access tokens?

Yes. Any JWT can be decoded regardless of its purpose. The claims are displayed the same way — you'll see the token type from the typ header and any custom claims the issuer included.

3Can I pipe a generated key straight into the JWT signer?

Yes. The JWT Key Generator tool outputs a secret or key that flows directly into the JWT tool's secret field via the pipeline. Generate a key, then sign a token with it in one flow.

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All 95 tools run locally on your Mac. No internet required, no data sent to servers.

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