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Documentation Core Tools Jwt Parser

Advanced Features

This guide covers the advanced features and capabilities of the JWT Parser tool for power users and developers.

History Management

Automatic History Tracking

The tool automatically saves parsed tokens to your browser's local storage:

  • Persistent Storage: History survives browser restarts
  • Privacy Focused: Data stays in your browser only
  • Automatic Cleanup: Limited to 50 recent tokens

History Operations

  • Load from History: Click any history item to reload that token
  • Clear History: Remove all stored tokens at once
  • Selective Loading: Choose specific tokens for re-analysis

History Information

Each history entry shows:

  • Algorithm: The signing algorithm used
  • Expiration: When the token expires
  • Timestamp: When the token was parsed
  • Token Preview: First 50 characters of the token

Token Analysis Features

Algorithm Detection

The tool automatically identifies and displays:

  • Symmetric Algorithms: HS256, HS384, HS512
  • Asymmetric Algorithms: RS256, RS384, RS512, ES256, ES384, ES512
  • None Algorithm: Unsecured tokens (for development only)

Expiration Analysis

  • Expiration Time: Converts Unix timestamp to readable date/time
  • Time Zone: Displays in your local timezone
  • Expired Tokens: Clearly indicates if token has expired

Claims Analysis

  • Standard Claims: Automatically identifies RFC 7519 standard claims
  • Custom Claims: Displays any application-specific claims
  • Nested Objects: Handles complex payload structures

Copy and Export Features

Structured Copy

When you copy results, you get:

Header:
{
  "alg": "HS256",
  "typ": "JWT"
}

Payload:
{
  "sub": "1234567890",
  "name": "John Doe",
  "iat": 1516239022,
  "exp": 1516242622
}

Signature:
SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

Use Cases for Copying

  • Documentation: Include in API documentation
  • Debugging: Share with team members for analysis
  • Testing: Use in automated test scenarios
  • Reports: Include in security audit reports

Error Handling and Validation

Format Validation

The tool performs comprehensive format checking:

  • Structure Validation: Ensures exactly 3 parts separated by dots
  • Base64URL Validation: Verifies each part is valid base64url
  • JSON Validation: Ensures header and payload are valid JSON

Error Messages

Clear, actionable error messages:

  • Invalid Format: Specific guidance on JWT structure
  • Parse Errors: Detailed information about parsing failures
  • Encoding Issues: Help with base64url encoding problems

Integration Patterns

Development Workflow Integration

  1. API Testing: Parse tokens from API responses
  2. Authentication Debugging: Analyze tokens during development
  3. Code Review: Verify token structure in pull requests
  4. Documentation: Generate examples for API docs

Testing Integration

  • Unit Tests: Use parsed data in test assertions
  • Integration Tests: Verify token structure in test scenarios
  • Security Tests: Analyze tokens for security vulnerabilities

Performance Considerations

Client-Side Processing

  • No Network Calls: All parsing happens in your browser
  • Fast Processing: Instant results for most tokens
  • Memory Efficient: Minimal memory footprint
  • Offline Capable: Works without internet connection

Large Token Handling

  • Size Limits: Handles tokens up to browser memory limits
  • Performance: Optimized for typical JWT sizes
  • Error Handling: Graceful handling of oversized tokens

Browser Compatibility

Supported Browsers

  • Chrome: Full support (recommended)
  • Firefox: Full support
  • Safari: Full support
  • Edge: Full support

Required Features

  • Local Storage: For history functionality
  • Clipboard API: For copy functionality
  • JSON Parsing: For token analysis

Security Best Practices

Token Handling

  • Never Log Tokens: Avoid logging sensitive tokens
  • Secure Environment: Use only in secure, private environments
  • Regular Cleanup: Clear history regularly
  • Access Control: Ensure only authorized users access the tool

Data Privacy

  • Local Storage Only: No data sent to external servers
  • Browser Isolation: Data stays in your browser
  • No Persistence: Clear data when switching contexts

Troubleshooting

Common Issues

  1. Token Not Parsing: Check format and encoding
  2. History Not Saving: Verify browser supports local storage
  3. Copy Not Working: Check browser clipboard permissions
  4. Display Issues: Try refreshing the page

Debug Tips

  • Check Console: Look for JavaScript errors
  • Verify Format: Ensure token has correct structure
  • Test with Examples: Use the built-in example token
  • Clear Cache: Try clearing browser cache if issues persist

API Reference

Token Structure

interface ParsedJWT {
  header: string; // Formatted JSON string
  payload: string; // Formatted JSON string
  signature: string; // Raw signature
}

interface JWTInfo {
  algorithm: string; // Signing algorithm
  type: string; // Token type
  expires: string; // Expiration time
}

History Structure

interface HistoryRecord {
  id: string; // Unique identifier
  token: string; // Full JWT token
  algorithm: string; // Signing algorithm
  expires: string; // Expiration time
  timestamp: number; // Parse timestamp
}

Next Steps

Explore Security Considerations for important security guidelines, or check out Examples for real-world usage scenarios.

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