Developer Tools for Random Data Generation // v2.13.1
root@generate-random:~/jwt-tokens$ _

Random JWT Token Generator

Generate JSON Web Tokens (JWT) for API authentication, testing, and development with customizable algorithms, claims, and expiration times

Our JWT token generator creates secure JSON Web Tokens (JWT) for API authentication, OAuth implementations, session management, and microservices security. Generate JWT tokens with configurable signing algorithms (HS256, HS384, HS512, RS256, RS384, RS512), custom expiration times, roles, scopes, and standard claims (iss, sub, aud, iat, exp). Perfect for API security testing, authentication system development, OAuth server testing, and validating JWT parsing libraries. JSON Web Tokens provide stateless authentication using a compact, URL-safe format with three parts: header (algorithm and type), payload (claims about the user), and signature (verification hash). Use our generator for secure JWT creation in API development, authentication testing, microservices authorization, and educational demonstrations of token-based security.

What is a JWT Token Generator?

A JWT (JSON Web Token) generator creates secure, compact tokens for stateless authentication and authorization in modern web applications and APIs. JWTs consist of three Base64URL-encoded parts separated by dots: **header.payload.signature**. The header specifies the signing algorithm (HMAC, RSA, or ECDSA) and token type. The payload contains claims - statements about the user and metadata like issuer (iss), subject (sub), audience (aud), issued-at time (iat), expiration (exp), and custom claims (roles, permissions). The signature ensures integrity by hashing the header and payload with a secret key (HMAC algorithms) or private key (RSA algorithms), preventing tampering and allowing verification without server-side session storage.

Our generator supports industry-standard algorithms: HS256/HS384/HS512 (HMAC with SHA-256/384/512) for symmetric signing using shared secrets, and RS256/RS384/RS512 (RSA with SHA-256/384/512) for asymmetric signing using private/public key pairs. Each generated token includes a cryptographically random secret, configurable expiration (1 hour to 1 year), and standard JWT claims following RFC 7519. Optional role and scope claims enable role-based access control (RBAC) and OAuth-style permission scopes. Use JWT generation for testing authentication flows, developing OAuth/OpenID Connect providers, validating JWT parsing libraries, demonstrating token-based security concepts, and creating realistic test data for API security testing.

JWT Token Generator Configuration

Count (1-10 Tokens)

Specify how many JWT tokens to generate (maximum 10 to prevent performance issues). Each token receives a unique secret key (for HMAC algorithms) and unique claims including jti (JWT ID using UUID v4), sub (random user identifier), and iat (current timestamp). Multiple tokens are useful for testing token rotation, concurrent sessions, and multi-user scenarios.

Algorithm (HS*/RS*)

Select signing algorithm: HS256/HS384/HS512 use HMAC (symmetric) with 64-character hex secrets suitable for single-server APIs. RS256/RS384/RS512 use RSA (asymmetric) requiring separate private/public keys, ideal for distributed systems and third-party verification. HS256 (HMAC-SHA256) is the most common default. Higher numbers (384, 512) provide stronger security at the cost of larger signatures.

Expiration Time (1 hour - 1 year)

Control token lifetime via exp claim. Short expirations (1 hour, 1 day) enhance security by limiting exposure if tokens leak, suitable for session tokens and access tokens. Longer expirations (7 days, 30 days, 1 year) reduce re-authentication frequency, appropriate for refresh tokens or remember-me functionality. Balance security (shorter is safer) with user experience (longer is more convenient).

Include Roles/Scope Claims

Enable to add authorization claims. Roles claim includes array ["user"] (customizable) for role-based access control (RBAC). Scope claim includes space-separated permissions "read write" for OAuth-style scopes. These claims enable fine-grained authorization checks beyond simple authentication, allowing APIs to verify not just "who" but also "what they can do".

How to Generate JWT Tokens

[STEP 1] Configure Token Parameters

Choose count (1-10), signing algorithm (HS256 for shared secrets, RS256 for public/private keys), and expiration time. For API authentication testing, use HS256 with 1 hour expiration. For OAuth/SSO testing, consider RS256 with longer expirations. Select algorithm based on your architecture: symmetric (HS*) for single-server, asymmetric (RS*) for distributed.

[STEP 1] Enable Optional Claims

Check "Include Roles" to add RBAC capabilities with a roles array claim. Check "Include Scope" to add OAuth-style permission scopes. These claims enable fine-grained authorization testing beyond basic authentication. Leave unchecked for minimal tokens with only standard claims (iss, sub, aud, iat, exp, jti).

[STEP 1] Generate & Inspect Tokens

Click EXECUTE GENERATION to create JWT tokens with cryptographically secure secrets. Each token displays with a Copy button for easy clipboard access. Expand "VIEW PAYLOAD & SECRET" to inspect the JSON payload (claims), secret key (for HMAC algorithms), header details, and algorithm. Verify claims include correct timestamps and unique identifiers.

[STEP 1] Use in Testing & Development

Copy tokens for API testing tools (Postman, cURL) by adding "Authorization: Bearer " headers. Use the provided secret to configure your JWT verification middleware. Export as JSON to include in test fixtures or automated test suites. Tokens are fully compliant with RFC 7519 and work with standard JWT libraries (jsonwebtoken, jose, php-jwt, etc.).

JWT Token Best Practices

  • _ HTTPS Only - Always transmit JWTs over HTTPS/TLS to prevent interception. Tokens sent over HTTP can be stolen via man-in-the-middle attacks. Never embed JWTs in URLs (visible in logs).
  • _ Secret Management - Keep signing secrets confidential. For HMAC (HS*), use cryptographically strong secrets (minimum 256 bits). For RSA (RS*), protect private keys and distribute public keys. Rotate secrets periodically.
  • _ Short Expiration Times - Use brief exp times for access tokens (15 minutes to 1 hour). Implement refresh tokens for longer sessions. Short expirations limit damage from stolen tokens while refresh tokens enable seamless re-authentication.
  • _ Validate All Claims - Server-side verification must check: signature validity, expiration (exp > current time), not-before (nbf ≤ current time if present), issuer (iss matches expected), audience (aud matches your service).
  • _ Avoid Sensitive Data in Payload - JWTs are Base64-encoded, not encrypted. Anyone with the token can decode the payload. Never include passwords, credit cards, or PII. Use JWE (JSON Web Encryption) for confidential data.
  • _ Token Revocation Strategy - JWTs are stateless and cannot be invalidated until expiration. Implement token blacklisting, maintain short expirations with refresh tokens, or use jti claim for tracking. Consider hybrid approaches combining JWT benefits with revocation capabilities.

Technical Implementation

Our JWT generator follows RFC 7519 specification, creating compact tokens with cryptographically signed payloads ensuring integrity and authenticity:

// JWT Generation Algorithm (RFC 7519)
Algorithm: JSON Web Token Creation with HMAC/RSA Signing

// Step 1: Create Header
header = {
  "typ": "JWT",
  "alg": algorithm (e.g., "HS256", "RS256")
}
encoded_header = base64url_encode(json_encode(header))

// Step 2: Build Payload with Claims
current_time = unix_timestamp()
payload = {
  "iat": current_time (issued at),
  "exp": current_time + expires_in (expiration),
  "jti": random_uuid_v4() (JWT ID),
  "iss": issuer (e.g., "api.example.com"),
  "sub": subject (e.g., "user_1234"),
  "aud": audience (e.g., "https://example.com")
  // Optional: "roles": ["admin", "user"], "scope": "read write"
}
encoded_payload = base64url_encode(json_encode(payload))

// Step 3: Create Signature
unsigned_token = encoded_header + "." + encoded_payload
if (algorithm starts with "HS") then:
  secret = random_bytes(32) as hexadecimal (64 chars)
  signature = HMAC_SHA(unsigned_token, secret)
else if (algorithm starts with "RS") then:
  signature = RSA_SHA(unsigned_token, private_key)
encoded_signature = base64url_encode(signature)

// Step 4: Concatenate Final Token
jwt_token = encoded_header + "." + encoded_payload + "." + encoded_signature
Example: eyJ0eXAiOiJKV1QiLCJhbGc...

// Format: header.payload.signature (Base64URL parts)
Verification: Recalculate signature and compare with provided

API Access for Developers

Generate JWT tokens programmatically using our free REST API. Specify algorithm, expiration, and optional claims for automated testing and CI/CD pipelines.
GET https://generate-random.org/api/v1/generate/jwt-token?count=1&algorithm=HS256&expires_in=3600&include_roles=true
VIEW FULL API DOCUMENTATION

Frequently Asked Questions

What is the difference between HS256 and RS256 algorithms?

HS256 (HMAC-SHA256) uses symmetric encryption with a shared secret - both token creation and verification use the same key. Suitable for single-server applications where the server both creates and verifies tokens. RS256 (RSA-SHA256) uses asymmetric encryption with a private key for signing and public key for verification. Ideal for distributed systems, microservices, or third-party integrations where you want others to verify tokens without giving them signing capability. RS256 is more secure for multi-service architectures but requires key management infrastructure.

Can I use these tokens in production applications?

These tokens are cryptographically valid and follow RFC 7519 standards, but they are intended for testing, development, and educational purposes only. Production systems should generate JWTs server-side using established libraries with proper secret management, key rotation, and security controls. Never expose signing secrets publicly. For production, use environment variables or key management services (AWS KMS, Azure Key Vault, HashiCorp Vault) to store secrets securely.

How do I verify a JWT token?

Use a JWT library in your programming language to decode and verify. Verification checks: (1) Signature validity using the secret/public key, (2) Expiration time (exp claim), (3) Issued-at time is not in future (iat claim), (4) Not-before time if present (nbf claim), (5) Issuer matches expected value (iss claim), (6) Audience matches your service (aud claim). Only trust tokens that pass all checks. Popular libraries: jsonwebtoken (Node.js), PyJWT (Python), php-jwt (PHP), jose (multiple languages).

What claims should I include in my JWT payload?

Standard claims (RFC 7519): iss (issuer - who created token), sub (subject - user identifier), aud (audience - intended recipient), exp (expiration timestamp), nbf (not before timestamp), iat (issued at timestamp), jti (JWT ID for tracking). Common custom claims: roles (array of user roles), scope (OAuth permissions), email, username, user_id. Avoid sensitive data (passwords, credit cards) as JWTs are Base64-encoded not encrypted. Keep payloads small to minimize token size in HTTP headers.

Why do JWT tokens have such long expiration times available?

Different token types require different lifetimes. Access tokens (used for API requests) should be short-lived (15 minutes to 1 hour) for security. Refresh tokens (used to obtain new access tokens) can be longer (7-30 days) for user convenience. Remember-me tokens might last months. Our generator offers 1 hour to 1 year to accommodate various use cases in testing. In production, use refresh token rotation - short-lived access tokens with longer refresh tokens that can be revoked if compromised.

How are JWTs different from session cookies?

Session cookies store a session ID referencing server-side session data (stateful). JWTs contain all user data in the token itself (stateless) requiring no database lookup, enabling horizontal scaling and microservices. Trade-offs: JWTs cannot be revoked until expiration (use short lifetimes + refresh tokens), are larger than session IDs (impacts bandwidth), and expose claims to clients (Base64-decoded). Sessions are revocable immediately but require shared session storage (Redis, database). Choose JWTs for distributed systems and APIs, sessions for traditional server-rendered web apps with centralized infrastructure.