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Advanced JWT Debugger & Validator

Professional JWT decoding, signature verification, and claim validation tool

security Secure Decoding verified Signature Verification rule Claim Validation history Token History

JWT Analysis

Format:

Signature Verification

settings Header

JWT header will appear here

person Payload

JWT payload will appear here

fingerprint Signature

Signature verification result
0
Token Size
0
Header Size
0
Payload Size
-
Signature

Claim Validation & Security Analysis

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Enter a JWT to analyze claims and security

Standard JWT Claims

iss
Issuer
Token issuer identity
String or URI
sub
Subject
Token subject identifier
String or URI
exp
Expiration Time
Token expiration timestamp
NumericDate
iat
Issued At
Token issuance timestamp
NumericDate

security Security Recommendations

info

Enter a JWT to get security analysis

We'll analyze your token for common security issues

Recent Tokens

history

No recent tokens

Quick Actions

JWT Technical Details

How JWT Debugger Works

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Base64URL Decoding

Decodes JWT parts from Base64URL format without external libraries

verified

Signature Verification

Verifies token signatures using Web Crypto API for client-side security

schedule

Claim Validation

Validates exp, nbf, iat claims against current time and checks issuer

security

Security Analysis

Analyzes tokens for common vulnerabilities and security misconfigurations

What is a JWT (JSON Web Token)?

A JSON Web Token (JWT) is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. This information can be verified and trusted because it is digitally signed.

JWT Structure

A JWT consists of three parts separated by dots (.):

  1. Header: Contains token type and signing algorithm (e.g., HS256, RS256)
  2. Payload: Contains the claims (statements about an entity)
  3. Signature: Used to verify the token hasn't been altered

Common JWT Use Cases

verified_user

Authentication

Once user is logged in, each subsequent request includes the JWT, allowing the user to access routes, services, and resources permitted with that token.

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Information Exchange

JWTs are a good way of securely transmitting information between parties because they can be signed using public/private key pairs.

Best Practices for JWT Security

  • check Use strong algorithms: Prefer RS256 or ES256 over HS256 for server-side verification
  • check Set reasonable expiration: Keep token lifetime short (15-60 minutes for access tokens)
  • check Validate all claims: Always check exp, nbf, iss, aud claims on the server
  • check Store securely: Store tokens in HTTP-only cookies or secure browser storage