SoftnagFree

JWT Decoder

PopularDeveloper Tools

Decode, inspect, and validate JSON Web Tokens (JWT) to view Header algorithms, Payload claims, expiration timestamps, and signature status.

100% In-Browser Privacy
Zero Server Uploads

Encoded JWT String

Header (Algorithm & Token Type)
{
  "alg": "HS256",
  "typ": "JWT"
}
Payload (Claims & Data)
{
  "sub": "1234567890",
  "name": "Aakash Sharma",
  "admin": true,
  "iat": 1516239022,
  "exp": 1916239022
}

Token Expiry & Status

Expiration (exp):9/21/2030, 4:37:02 PM (Valid)
Issued At (iat):1/18/2018, 1:30:22 AM
In-Browser Security:

Decoded entirely on your device via client-side base64url routines. No token strings are transmitted to remote servers.

Who Is JWT Decoder Built For?

Full-stack developers debugging OAuth 2.0 and OpenID Connect (OIDC) authentication flows
Security engineers auditing token expiration, issuer claims, and audience permissions
Frontend engineers inspecting user roles and permission scopes stored in ID tokens

Key Benefits & Core Capabilities

Instant Header & Payload Inspection

Decodes Base64Url-encoded JWT parts into formatted, syntax-highlighted JSON objects.

Live Expiration & Issued-At Timer

Automatically parses exp, iat, and nbf claims with human-readable timestamps and expired status warnings.

Signature Verification Check

Verify HMAC (HS256) signatures by providing your secret key in your browser.

Client-Side Privacy

Decode production JWTs and auth tokens safely without sending credentials to third-party servers.

Step-by-Step Guide: How to Use JWT Decoder

  1. 1
    Paste TokenPaste any encoded JWT string.
  2. 2
    Inspect ClaimsView color-coded Header, Payload, and expiration status.
  3. 3
    Copy JSONCopy parsed JSON with one click.

How It Works & Technical Architecture

A JSON Web Token consists of three base64url-encoded segments separated by dots: Header, Payload, and Signature (header.payload.signature).

The Softnag JWT Decoder splits the token, decodes the URL-safe base64 strings into UTF-8 JSON text, and parses standard RFC 7519 registered claims (sub, iss, aud, exp, nbf, iat).

Because all decoding and signature verification execute locally in client memory using Web Crypto, sensitive customer authentication tokens remain completely confidential.

Practical Use Cases & Applications

Debugging OAuth & Auth0 Tokens

Inspect access tokens and ID tokens issued by Auth0, Firebase, AWS Cognito, and Okta.

Checking Token Expiration Status

Instantly check whether a token has expired and view its exact expiration date and time.

Auditing Role-Based Permissions

Verify user roles, scopes, and custom metadata claims attached to session tokens.

Verifying Signature Integrity

Test HMAC-SHA256 signatures with your application secret to ensure tokens have not been tampered with.

Supported Formats & Input Options

JWT Strings (header.payload.signature)Base64URL encoded tokens

Frequently Asked Questions

Is it safe to paste live production JWT tokens into this tool?

Yes. Softnag decodes JWT tokens 100% locally in your browser. Unlike traditional online decoders, zero token data is ever transmitted over the network.

Can this tool verify if a JWT has been tampered with?

Yes. If you provide your HMAC secret key, Softnag recalculates the cryptographic signature locally using Web Crypto to verify integrity.

Why does my token say "Expired"?

The "exp" (expiration time) claim in the token payload represents a Unix timestamp that has already passed. The tool highlights expired tokens in red.

What token algorithms are supported?

The decoder parses all standard JWT algorithms (HS256, HS384, HS512, RS256, ES256, EdDSA).

Can I copy the decoded payload as clean JSON?

Yes. You can copy the decoded Header or Payload JSON with a single click.

Are my tokens sent to any server?

Never. Softnag parses JWTs 100% locally via browser Base64Url decoding routines.