About JWT Decoder & Inspector
Product Documentation, Architecture & Offline Privacy Verification
What It Does
Decode and inspect JWT headers, payloads, claims, and timestamps locally in your browser.
How It Works
Key Features
- Instant Local Decoding: Decode the header, payload, and signature instantly. No server processing, zero latency.
- Standard Claim Parsing: Automatically parse and display human-readable timestamps for exp, iat, and nbf claims.
- 100% Client-Side Privacy: Your sensitive tokens never leave your browser. Zero network requests are made during decoding, ensuring maximum privacy for your credentials.
Limitations & Compatibility
Frequently Asked Questions
What is a JWT?
JWT (JSON Web Token) is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object.
How do I decode a JWT?
Simply paste your JSON Web Token into the text area above. The tool will automatically decode the Base64URL-encoded header and payload to reveal the JSON data inside.
Can I decode a JWT without the secret key?
Yes. The header and payload of a standard JWT are only Base64URL encoded, not encrypted. Anyone can decode and read the contents without the secret key. The secret key is only required to verify the signature.
Does decoding a JWT verify its signature?
No. Decoding only reveals the encoded contents. It does not prove the token was issued by a trusted party. Do not assume a successfully decoded JWT is valid or secure without separate cryptographic verification.
Is Base64 the same as encryption?
No. Base64 (and Base64URL) is merely a data encoding format used to represent binary data in an ASCII string format. It provides zero cryptographic security.
What do exp, iat, and nbf mean?
These are standard registered claims. `exp` (Expiration Time) identifies when the token expires. `iat` (Issued At) identifies when the token was issued. `nbf` (Not Before) identifies the time before which the token must not be accepted.
Can JWTs contain sensitive information?
Yes, but they shouldn't. Because standard JWTs are encoded rather than encrypted, you should never place passwords, API keys, or other sensitive secrets inside the payload.
Does KreateKode upload my JWT?
No. Your JWT is processed locally in your browser. KreateKode does not need to upload the token to decode its Base64URL-encoded header and payload. Zero network requests are made.
What does the alg field mean?
The `alg` field in the JWT header indicates the cryptographic algorithm used to secure the token (e.g., HS256, RS256). An algorithm of `none` means the token is unsecured and should generally be rejected.
What does an expired JWT mean?
An expired JWT has an `exp` claim timestamp in the past. It means the token should no longer be accepted for authentication or authorization by your application.
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100% private, instant offline processing directly in your browser with zero data retention.
