JWT Decoder and Verifier

Tool for decoding and verifying JSON Web Tokens (JWT)

This online JWT decoder and verifier allows you to decode JWT tokens and verify their signatures with multiple algorithms.

Quickly decode JWT tokens and verify JWT signatures in your browser with no server upload.

JWT Token

Decoded Token

Verification

Signature Not Verified
Only HMAC algorithms (HS256, HS384, HS512) are supported in the browser.

About JWT Decoder and Verifier

JWT (JSON Web Token) is a compact, URL-safe means of representing claims to be transferred between two parties. This tool allows you to decode JWT tokens to inspect their header and payload data, and verify their signatures.

Key features:

  • Decode JWT tokens to view header and payload information
  • Verify JWT signatures using various algorithms (HS256, RS256, etc.)
  • Support for both symmetric (HMAC) and asymmetric (RSA, ECDSA) algorithms
  • Option for Base64-encoded secrets

JWT structure:

  • Header - Contains the token type and signing algorithm
  • Payload - Contains the claims or assertions
  • Signature - Verifies the token hasn't been tampered with

This tool performs all operations in your browser - no data is sent to any server.

Security & Authentication Applications

Web Application Security & Authentication

Essential for security engineers, authentication specialists, and backend developers implementing secure user authentication and authorization systems.

Authentication Applications:
  • User login and session management
  • Single Sign-On (SSO) implementation
  • OAuth 2.0 and OpenID Connect flows
  • Multi-factor authentication (MFA) integration
API Security & Access Control

Critical for API developers, cybersecurity specialists, and DevSecOps engineers securing API endpoints and implementing fine-grained access control mechanisms.

API Security Applications:
  • RESTful API authentication and authorization
  • Microservices inter-service communication
  • GraphQL query authorization
  • Rate limiting and API gateway integration
Enterprise Security & Identity Management

This JWT decoder supports enterprise security teams, identity architects, and compliance specialists working with large-scale authentication systems.

Enterprise Applications:
Identity providersLDAP integrationSAML federationRole-based accessAudit loggingCompliance monitoring

API Development & Microservices Applications

REST API & Web Services Development

Essential for API developers, backend engineers, and integration specialists building secure, scalable web services with stateless authentication mechanisms.

API Development Applications:
  • RESTful API endpoint protection
  • Bearer token authentication implementation
  • API versioning and deprecation management
  • Third-party API integration and testing
Microservices Architecture & Cloud Native

Critical for microservices architects, cloud engineers, and distributed systems specialists implementing secure service-to-service communication and cloud-native authentication.

Microservices Applications:
  • Service mesh authentication (Istio, Linkerd)
  • Container-based authentication strategies
  • Kubernetes RBAC and service accounts
  • Event-driven architecture security
DevOps & CI/CD Integration

This decoder facilitates DevOps engineers, automation specialists, and platform teams integrating JWT authentication into deployment pipelines.

DevOps Applications:
CI/CD pipeline authDeployment tokensInfrastructure as CodeSecret managementMonitoring integrationHealth check endpoints

Technical Standards & JWT Implementation

RFC Standards & JWT Specifications

Following IETF standards and industry specifications ensures JWT compatibility, security, and interoperability across different platforms and implementations.

Technical Standards:
  • RFC 7519 JSON Web Token (JWT) specification
  • RFC 7515 JSON Web Signature (JWS) compliance
  • RFC 7516 JSON Web Encryption (JWE) support
  • RFC 7517 JSON Web Key (JWK) management
Cryptographic Algorithms & Security

Understanding cryptographic algorithms, key management, and security best practices ensures robust JWT implementation and vulnerability prevention.

Cryptographic Implementation:
  • HMAC-SHA256 (HS256) symmetric signing
  • RSA with SHA-256 (RS256) asymmetric signing
  • ECDSA with P-256 and SHA-256 (ES256)
  • Key rotation and management strategies
Security Best Practices & Vulnerability Prevention

Proper JWT implementation requires understanding of security vulnerabilities, attack vectors, and mitigation strategies to prevent common authentication bypasses.

Security Considerations:
Algorithm confusionToken expirationSignature verificationSecret managementReplay attacksCSRF protection

Security Warning: Always validate JWT signatures, verify expiration times, and use secure key management practices to prevent authentication bypasses and token manipulation.

For JWT technical specifications, visit RFC 7519 JWT Standard and for security best practices, see JWT Security Best Practices.