Online JWT Converter (Decode JWT to JSON)

Category: Developer · URL: /tools/online-jwt-converter.html

JWT Input

Paste a token like header.payload.signature (JWS). No network requests.

Output

Decoded JSON (header/payload) + encoded parts + time claim conversions.

Encode (alg:none) — optional

Creates an alg:none token with an empty signature (ends with a dot). This tool does not sign tokens.

Header JSON

Payload JSON

Privacy: runs locally in your browser. No uploads, no tracking scripts.

How to use

Use it to decode or create simple test tokens.

Paste a JWT into JWT Input.
Click Decode JWT to view header/payload JSON and derived time claims.
Optionally, use Encode (alg:none) to create an unsigned token from header/payload JSON for testing.

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Secondary intents covered: Decode a JWT and read the header and payload as JSON, Validate that a token has 3 parts and is valid Base64URL, Pretty-print claims for debugging and copy them, Inspect the signature segment without verifying it, Convert exp/iat/nbf timestamps to human-readable UTC dates, Create an unsigned JWT (alg:none) for local testing, Troubleshoot common decode errors (bad padding, invalid JSON), Extract specific claims like sub, iss, aud, exp, Compare encoded parts vs decoded JSON, Keep token data local (no server calls)

FAQ

Does this JWT converter verify the signature?

No. It only decodes and shows the signature segment; use a signing/verifying tool for cryptographic verification.

Is my token sent to a server?

No. The decoder runs locally in your browser and does not make network requests.

Why do I get “JWT must have 3 parts”?

A JWS JWT must be header.payload.signature. If it has fewer/more segments, it won’t decode as a JWT.

Why does decoding fail with “invalid Base64URL length/characters”?

The token contains characters outside Base64URL or has a malformed segment length; re-copy the token without spaces or quotes.

What are exp, iat, and nbf in the output?

They are standard time claims (seconds since Unix epoch). The tool also shows them converted to UTC ISO timestamps.

What does “Encode (alg:none)” mean?

It generates an unsigned token for testing. Many real systems reject alg:none tokens for security.

Can this tool convert a JWT to only the payload JSON?

Yes—decode it and then copy the decoded.payload section from the output.