🛡️ JWT Token Decoder & Inspector Security

Decode JSON Web Token (JWT) headers and payloads, check token expiration timestamps, and inspect claims.

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JWT Token Decoder & Inspector — Interactive Browser Workspace

All uploaded files and input data are processed strictly inside your local device RAM via WebAssembly.

🔒 100% In-Browser Privacy · Zero Server Uploads

📖 How to Use JWT Token Decoder & Inspector? (Step-by-Step Guide)

Step 1

Copy your JSON Web Token (`eyJ...`) from your browser storage, Authorization header, or OAuth response.

Step 2

Paste the token string into the JWT input field.

Step 3

Instantly inspect the decoded JSON Header (algorithm & key ID) and Payload claims (`sub`, `iat`, `exp`, roles).

Step 4

Check the human-readable expiration (`exp`) timestamp status to diagnose 401 Unauthorized session errors.

⚙️ IETF RFC 7519 JSON Web Token (JWT) Inspection & Base64URL Claim Parsing

JSON Web Tokens (RFC 7519) are the industry standard for stateless authentication across OAuth 2.0, OpenID Connect (OIDC), and microservice APIs. A JWT consists of three dot-separated Base64URL segments: `Header.Payload.Signature`.

Pasting active production Bearer tokens into third-party websites risks session hijacking if those sites log requests. DH Tools decodes the JOSE Header (`alg`, `typ`, `kid`) and Payload claims (`iss`, `sub`, `aud`, `exp`, `iat`) strictly inside your local browser memory.

📊 Technical Specifications & Architecture

Specification	IETF RFC 7519 (JWT) & RFC 7515 (JWS)
Segments Parsed	JOSE Header, JWT Claims Payload & Signature
Algorithms	HS256, HS384, HS512, RS256, ES256, EdDSA
Security	100% Local RAM (Zero Token Leakage)

🎯 Real-World Industry Use Cases

✓ Debugging 401 Unauthorized API Errors Check whether a Bearer token's `exp` timestamp has expired or `aud`/`iss` claims mismatch.

✓ Inspecting OAuth2 & OIDC ID Tokens Verify user roles, permissions, and custom claims returned by Auth0, Firebase, Cognito, or Keycloak.

✓ Frontend & Mobile Auth Development Inspect localStorage or cookie JWT payloads during login flow implementation.

✓ Security & Penetration Auditing Check tokens for insecure `alg: none` headers or accidentally exposed PII in claims.

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🛡️ Why Use DH Tools JWT Token Decoder & Inspector?

100% Privacy & Security

All files process locally in your device's memory (RAM). Nothing is uploaded to remote servers or saved on external disks.

Instant Processing

No upload queues, network bottlenecks, or server wait times. Near instantaneous execution powered by WebAssembly.

Cross-Platform Ready

Fully responsive on desktop, tablet, and mobile with offline-enabled Progressive Web App capabilities.

❓ Frequently Asked Questions

Yes, because DH Tools runs 100% client-side in your browser with zero network requests. Unlike cloud debuggers, your active Bearer token is never transmitted over the internet.

In standard JWS (JSON Web Signature - RFC 7519), the Header and Payload segments are simply Base64URL-encoded JSON, not encrypted! The secret or private key is only used to compute the 3rd segment (Signature) to prevent tampering.

They are Unix Epoch timestamps in seconds: `iat` (Issued At) is when the token was created, `exp` (Expiration Time) is when the token expires, and `nbf` (Not Before) is when it becomes active.

Because anyone who intercepts or views a JWS token can Base64URL-decode its payload in milliseconds. Only store non-sensitive identifiers (`sub`, `role`, `exp`) inside JWT claims.