Free JWT Encoder | Decoder

🔓 JWT Decoder

Paste your JWT token below to decode and view its contents

JWT Token:

Header

Payload

Signature

Token Information

Algorithm

-

Type

-

Issued At

-

Expires At

-

⚠️ Invalid JWT Token

🔒 JWT Encoder

Create a JWT token by providing header, payload, and secret

Header (JSON): {\n "alg": "HS256",\n "typ": "JWT"\n}

Payload (JSON): {\n "sub": "1234567890",\n "name": "John Doe",\n "iat": 1516239022\n}

Secret Key:

Algorithm: HS256 (HMAC-SHA256) HS384 (HMAC-SHA384) HS512 (HMAC-SHA512)

Generated JWT Token

⚠️ Encoding Error

✓ JWT Validator

Verify JWT token signature and check expiration

JWT Token:

Secret Key (for verification):

🔍 JWT Debugger

Debug and analyze JWT tokens with detailed information

JWT Token:

📊 Token Structure

📋 Claims Analysis

🔒 Security Analysis

Complete JWT Tools Suite

JSON Web Tokens (JWT) are an open standard (RFC 7519) for securely transmitting information between parties as a JSON object. Our comprehensive JWT tools suite provides everything developers need to work with JWT tokens including decoding, encoding, validating, and debugging capabilities.

What is a JWT Token?

A JSON Web Token consists of three parts separated by dots (.):

• Header: Contains the token type (JWT) and signing algorithm (e.g., HS256, RS256)
• Payload: Contains the claims or statements about an entity and additional data
• Signature: Used to verify the sender and ensure message integrity

🔓 JWT Decoder Features

Our JWT decoder tool allows you to:

• Decode any JWT token instantly without requiring a secret key
• View header, payload, and signature components separately
• See formatted JSON for easy reading and understanding
• Extract token metadata like algorithm, type, issued date, and expiration
• Copy individual sections for further use
• Identify token structure issues quickly

🔒 JWT Encoder Features

Create custom JWT tokens with our encoder:

• Generate JWT tokens with custom headers and payloads
• Support for HS256, HS384, and HS512 algorithms
• Add custom claims and metadata
• Specify your own secret key for signing
• Perfect for testing authentication flows
• Create tokens for API testing and development

✓ JWT Validator Features

Verify token authenticity and validity:

• Verify JWT signature using your secret key
• Check token expiration status
• Validate token structure and format
• Identify expired or invalid tokens
• Ensure tokens haven't been tampered with
• Comprehensive validation reports with detailed feedback

🔍 JWT Debugger Features

Advanced debugging and analysis:

• Detailed token structure analysis
• Claims inspection and validation
• Security recommendations and best practices
• Identify potential security issues
• Algorithm analysis and recommendations
• Time-based claims analysis (iat, exp, nbf)

Common JWT Use Cases

• Authentication: Verify user identity across requests without sessions
• Authorization: Control access to protected resources
• Information Exchange: Securely transmit data between parties
• Single Sign-On (SSO): Enable seamless authentication across multiple applications
• API Security: Protect REST APIs with stateless authentication
• Microservices: Authenticate requests between services

JWT Signing Algorithms Explained

Understanding JWT algorithms is crucial for security:

• HS256 (HMAC-SHA256): Symmetric algorithm using a shared secret key. Fast and simple.
• HS384 (HMAC-SHA384): Similar to HS256 but with longer hash for extra security
• HS512 (HMAC-SHA512): Highest security HMAC variant with 512-bit hash
• RS256 (RSA-SHA256): Asymmetric algorithm using public/private key pairs
• ES256 (ECDSA-SHA256): Elliptic curve algorithm, more efficient than RSA

JWT Security Best Practices

• Use Strong Secrets: Generate long, random secret keys (at least 256 bits)
• Set Expiration Times: Always include 'exp' claim to limit token lifetime
• Use HTTPS: Always transmit JWT tokens over encrypted connections
• Validate Everything: Check signature, expiration, and claims on every request
• Don't Store Sensitive Data: JWT payloads are easily decoded, avoid secrets
• Implement Refresh Tokens: Use short-lived access tokens with refresh mechanism
• Consider Algorithm Security: Use RS256 or ES256 for public-facing APIs
• Implement Token Revocation: Have a strategy to invalidate compromised tokens
• Validate Audience and Issuer: Use 'aud' and 'iss' claims to prevent token misuse

Common JWT Claims

Standard JWT claims (registered claims):

• iss (issuer): Identifies who issued the token
• sub (subject): Identifies the subject of the token (usually user ID)
• aud (audience): Identifies the intended recipient(s)
• exp (expiration): Timestamp when token expires
• nbf (not before): Timestamp before which token is invalid
• iat (issued at): Timestamp when token was created
• jti (JWT ID): Unique identifier for the token

Frequently Asked Questions

Is it safe to decode JWT tokens online?

Yes, our JWT decoder runs entirely in your browser using JavaScript. No tokens are sent to any server or stored anywhere. However, never paste tokens containing sensitive production data on any online tool. Use these tools for development and testing only.

Can I decode a JWT without the secret key?

Yes! JWT tokens are not encrypted, they're only signed. You can always decode and view the header and payload without a secret key. However, you need the secret key to verify the signature and ensure the token hasn't been tampered with.

What's the difference between encoding and encrypting?

JWT tokens are Base64URL encoded, not encrypted. This means anyone can decode and read the contents. The signature ensures integrity (data hasn't changed) but not confidentiality. Never put sensitive data like passwords in JWT payloads.

How long should JWT tokens be valid?

Best practice is to use short-lived access tokens (5-15 minutes) combined with longer-lived refresh tokens (days to weeks). This balances security with user experience. For highly sensitive operations, use even shorter expiration times.

What algorithm should I use for JWT?

For symmetric signing (same key for signing and verification), HS256 is most common. For asymmetric (public/private keys), use RS256 or ES256. RS256 is recommended for public-facing APIs where multiple parties need to verify tokens but shouldn't be able to create them.

Can JWT tokens be revoked?

JWT tokens are stateless by design and cannot be directly revoked. However, you can implement revocation by maintaining a blacklist of revoked tokens, using short expiration times, or implementing a token versioning system in your database.

Should I store JWT tokens in localStorage or cookies?

Both have trade-offs. Cookies with httpOnly and secure flags are generally more secure against XSS attacks. localStorage is vulnerable to XSS but easier to use with REST APIs. Consider using httpOnly cookies for web applications and implementing proper CSRF protection.

What is the 'none' algorithm vulnerability?

The 'none' algorithm allows unsigned tokens, creating a security vulnerability if servers don't properly validate the algorithm. Always explicitly specify allowed algorithms and reject tokens with 'none' or unexpected algorithms in production systems.