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RFC 7519 मानक और HMAC सत्यापन6 मिनट पढ़ने का समयअपडेट किया गया:

JWT टोकन संरचना और हस्ताक्षर सत्यापन: RFC 7519 तकनीकी गाइड

JWT के हेडर और पेलोड को लोकली डीकोड करें, HMAC-SHA256 हस्ताक्षर सत्यापित करें और टोकन समाप्ति की जांच करें।

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WEBioDD इंजीनियरिंग टीम•100% इन-ब्राउज़र और जीरो-ट्रस्ट

प्रमुख बातें

  • JWT में बिंदुओं द्वारा अलग किए गए 3 Base64URL भाग होते हैं: Header, Payload, और Signature।
  • हस्ताक्षर डेटा की अखंडता की पुष्टि करता है लेकिन डेटा को छिपाता नहीं है; पेलोड कोई भी पढ़ सकता है।
  • हमेशा exp और nbf दावों की पुष्टि करें ताकि रीप्ले हमलों से बचा जा सके।
  • उत्पादन वातावरण की गुप्त कुंजियों को कभी भी अविश्वसनीय ऑनलाइन प्लेटफ़ॉर्म पर पेस्ट न करें।
100% In-Browser & Local Execution

JWT टोकन डीकोड और डिबग करें

गुप्त कुंजियों को इंटरनेट पर भेजे बिना ब्राउज़र में हेडर, पेलोड और हस्ताक्षर का सुरक्षित विश्लेषण करें।

  • RFC 7519 compliant parser
  • HMAC-SHA256 signature verify
  • Live expiration countdown
  • 100% client-side execution
JWT डिबगर शुरू करें

01.JWT Token Anatomy: Header, Payload, and Signature

A JSON Web Token (JWT) is a compact, URL-safe string divided into three Base64URL-encoded segments: Header.Payload.Signature. The Header declares the signing algorithm (e.g., HS256 for HMAC-SHA256). The Payload contains claims (user ID, roles, expiration). The Signature is computed by hashing the encoded header and payload with a secret key, ensuring the token has not been tampered with.
typescriptClient-side JWT parsing without server transmission
// JWT Decoding Algorithm
function decodeJWT(token: string) {
  const [headerB64, payloadB64, signatureB64] = token.split('.');
  const header = JSON.parse(atob(headerB64.replace(/-/g, '+').replace(/_/g, '/')));
  const payload = JSON.parse(atob(payloadB64.replace(/-/g, '+').replace(/_/g, '/')));
  return { header, payload, signature: signatureB64 };
}

02.HMAC-SHA256 Signature Verification Process

To verify a JWT signature locally, concatenate the Base64URL-encoded header and payload with a dot, then compute HMAC-SHA256 using your secret key via Web Crypto API. Compare the result against the provided signature. A mismatch indicates tampering or an incorrect secret.
Never paste production secret keys into online JWT debuggers. Our tool runs 100% locally in your browser memory.

03.Token Expiration & Timestamp Claims

The exp claim (expiration time) is a Unix timestamp defining when the token becomes invalid. The nbf (not-before) claim prevents premature token usage. Always validate these claims on the server and display countdown timers to users in dashboards.

Local JWT Debugger vs. Remote Online Validators

Technical architectural comparison between local browser execution and cloud server processing.

Security AspectLocal Browser ToolThird-Party JWT.io Sites
Secret Key ExposureNever leaves browser memoryTransmitted over HTTPS POST
Token Payload PrivacyDecoded in local RAM onlySent to remote servers & logged
Validation LatencyInstant (sub-millisecond)150ms - 500ms network delay
Offline CapabilityWorks without internetFails when disconnected

How to Decode and Verify JWT Tokens

Step-by-step instructions for JWT inspection and validation.

1

Paste JWT Token

Copy your JWT string from API responses or browser cookies and paste into the debugger input field.

2

Inspect Header & Payload

View decoded JSON claims including user ID, roles, issued-at (iat), and expiration (exp) timestamps.

3

Verify Signature (Optional)

Enter your secret key to validate HMAC signature integrity (never use production keys on public tools).

4

Check Expiration Status

Review the live countdown timer showing time remaining until token expiry.

JWT Security Best Practices

  • ✓Always use HTTPS to prevent JWT interception during transmission.
  • ✓Set short expiration times (15-60 minutes) and refresh tokens via secure endpoints.
  • ✓Never store sensitive data in JWT payloads; they are NOT encrypted.
  • ✓Validate signatures and expiration timestamps on every API request server-side.

Frequently Asked Questions

No. JWT payloads are Base64URL-encoded, which is easily decoded. Never store passwords or PII in JWT claims.