JWT Token Generator
Generate signed JSON Web Tokens (JWT) directly in your browser. Customize claims, algorithms, expirations, and test authentication flows with HMAC HS256.
JWT Header & Payload Claims
Edit claims and sign in browser with HMAC-SHA256 (HS256).
Building and Testing JSON Web Tokens for Modern Authentication
JSON Web Tokens (JWT) are an open standard (RFC 7519) that defines a compact, URL-safe means for securely transmitting information between parties as a JSON object. JWTs are the bedrock of stateless authentication in modern OAuth 2.0, OpenID Connect, and microservice architectures. This tool enables developers to construct mock tokens, test authorization scopes, and verify cryptographic signatures client-side.
Key Technical Features
Client-Side Web Crypto Signing
Cryptographically signs tokens using the browser's native Web Crypto API with HMAC-SHA256 (HS256) without sending secrets to any external server.
Custom Claims & Scopes Editor
Easily edit subject (sub), audience (aud), issuer (iss), roles, permissions, and custom attributes.
Quick Expiration Presets
Set token expiration (exp) and issued-at (iat) timestamps with one click (+15 min, +1 hour, +24 hours, +7 days).
Color-Coded Token Breakdown
Visualizes the standard three-part structure: Header (Red), Payload (Purple), and Signature (Cyan).
Live Base64URL Encoding & Decoding
Instant two-way reflection between raw JSON structures and the encoded bearer token string.
Mock Auth Profile Presets
Quickly load Admin, Standard User, or Machine-to-Machine (M2M) API token payloads.
Engineering & DevOps Scenarios
- ✓API Developers & Backend Engineers
Generate mock authorization tokens to test protected endpoints in Postman, Insomnia, or cURL.
- ✓Frontend Developers
Mock user roles and permission flags in React/Vue/Angular applications before backend endpoints are ready.
- ✓QA Engineers & Pen Testers
Test expired token handling, invalid signature errors, and claim boundary conditions.
- ✓System Architects
Design clean payload schema structures for microservice token exchange protocols.
Frequently Asked Questions
How does a JWT token work?
A JWT consists of three parts separated by dots (.): Header, Payload, and Signature. The Header defines the token type and cryptographic algorithm. The Payload contains user claims and expiration dates. The Signature is created by hashing the encoded header and payload with a private secret key.
Is my secret key safe when using this generator?
Yes. This generator uses the browser's native window.crypto.subtle API entirely client-side. Your secret key and payload are never sent over the network to our servers.
What is the difference between HS256 and RS256?
HS256 is a symmetric algorithm using a shared secret key for both signing and verifying tokens. RS256 is an asymmetric algorithm using a private key to sign the token and a public key to verify it.
Can sensitive data be stored in a JWT payload?
No. The payload of a standard JWT is merely Base64URL-encoded, not encrypted. Anyone who intercepts the token can decode and view the claims. Never store passwords, API secret keys, or unencrypted Social Security numbers in a JWT payload.
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