JWT Debugger & Claims Inspector ProRFC 7519 Compliant
Decode, verify HMAC signatures, inspect expiration claims, and generate cryptographically signed JSON Web Tokens.
✓ Token is Active & Validin 3h
Expiration (exp): Tue, 20 Oct 2026 00:18:42 GMT
{
"alg": "HS256",
"typ": "JWT",
"kid": "key_2026_auth"
}{
"iss": "https://auth.docudev.site/",
"sub": "usr_9981a_enterprise",
"aud": "docudev-web-client",
"exp": 1792455522,
"nbf": 1792441062,
"iat": 1792441062,
"jti": "jwt_token_id_99a8b7c6",
"email": "alexandra.v@docudev.site",
"email_verified": true,
"name": "Alexandra Vance",
"roles": [
"enterprise_admin",
"billing_manager"
],
"org_id": "org_docudev_global"
}Signature verification executes directly via Web Cryptography API (`crypto.subtle`). Secrets and keys never leave your machine.
JWT Structural & Cryptographic Metadata
Cryptographically Secure JWT Inspection Studio
Safely decode sensitive authentication tokens without risking key leakage or server-side logging.
In-Browser HMAC Verification
Test secret keys against HS256, HS384, and HS512 signatures locally using the Web Crypto API without uploading secrets.
Live Expiration Alarms
Automatic real-time calculation of token expiry (`exp`), activation (`nbf`), and issue times (`iat`) with visual health status.
JWT Token Generator
Construct custom payload claims and sign tokens with custom expiration lifetimes for development and staging tests.
Frequently Asked Questions
Is it safe to paste production JWTs or API keys here?
Yes. Unlike traditional online decoders, DocuDev executes 100% in your local browser sandbox. No tokens, claims, or secrets are ever sent across a network.
What do the colors in the encoded JWT string mean?
Red corresponds to the JOSE Header, Purple represents the Payload / Claims body, and Cyan is the cryptographic Signature.
How does signature verification work?
For HMAC algorithms (HS256, HS384, HS512), the browser computes the cryptographic digest over `header.payload` and compares it to the signature in constant time.
Can I generate tokens for testing API endpoints?
Yes. Switch to the "JWT Generator & Signer" tab, specify your claims, expiration duration, and secret key, and generate valid signed tokens instantly.
How to Use JWT Debugger
Decode and inspect JSON Web Token headers, payload claims, and expiration dates. Follow the quick steps below to operate this tool with maximum speed and complete local privacy.
Step-by-Step Instructions
Simple, actionable steps to use JWT Debugger efficiently.
Enter Token
Paste your encoded JWT string (Header.Payload.Signature) into the input box.
Inspect Claims
View decoded JSON header parameters, payload claims, iss, sub, and exp expiration timestamps.
Copy Output
Copy decoded payload JSON directly to your clipboard for debugging.
How It Works & Capabilities
Technical advantages and operational functions of this tool.
1. In-Memory Input
Files or text inputs are ingested directly into active browser RAM. No temporary files or logs are ever transmitted to any external server.
2. Client-Side Processing
Calculations, transformations, and compilations are performed locally utilizing WebAssembly and modern JavaScript engines for real-time speed.
3. Instant Local Export
Save your results immediately to disk or copy data to clipboard. Outputs maintain complete original quality with zero watermarks.
Frequently Asked Questions
Clear answers about privacy, limitations, and how JWT Debugger functions.