JWT Generator – Generate Signed JWT Tokens Free Online
Generate signed JWT tokens with custom header and payload. HMAC-SHA256 signing in your browser. Free JWT generator — no sign-up, no upload.
Frequently Asked Questions
HMAC-SHA256 (HS256) — the most common symmetric JWT signing algorithm. The same secret is used to sign and verify the token.
The signing runs entirely in your browser using the Web Crypto API. Your secret is never sent to a server. Still, avoid using production secrets in browser tools — use it for development and testing.
exp is the expiration Unix timestamp. Tokens with an exp in the past are considered expired. Click 'Add exp (1h)' to add an expiry 1 hour from now.
This tool supports HS256 only. For asymmetric algorithms, use a server-side JWT library.
What is JWT Generator – Generate JWT Tokens Free Online?
A JWT generator creates signed JSON Web Tokens (JWTs) with a custom header, payload, and HMAC-SHA256 signature. JWTs are used for authentication and authorization in web APIs — they allow servers to verify a client's identity without storing session data. Our tool creates standard HS256-signed tokens entirely in your browser, useful for API testing, development, and learning JWT structure.
How to Use JWT Generator – Generate JWT Tokens Free Online
- 1Enter your HMAC secret key in the Secret field.
- 2Edit the payload JSON to include your desired claims (sub, iat, exp, etc.).
- 3The signed JWT token is generated instantly.
- 4Copy the token and use it in your API Authorization header.
- 5Verify the token using the JWT Decoder tool.
Key Features
- ✓HMAC-SHA256 (HS256) JWT signing
- ✓Custom header and payload JSON
- ✓Auto-sets iat (issued at) timestamp
- ✓Instant token generation
- ✓Runs entirely in your browser — secret never sent to server
Benefits
- →Generate test JWT tokens for API development
- →Learn JWT structure by building tokens manually
- →Create tokens for integration testing without a backend
- →Verify JWT signing behavior with custom payloads
Why Use Irreva for JWT Generator – Generate JWT Tokens Free Online?
Frequently Asked Questions
What is HS256 signing?
HS256 (HMAC with SHA-256) is a symmetric signing algorithm that uses a shared secret key. Both the issuer and validator use the same key. It is the most common JWT signing algorithm for single-server applications.
Is my secret key sent to a server?
No. The HMAC-SHA256 signing uses the Web Crypto API running entirely in your browser. Your secret key and payload never leave your device.
What is the exp claim?
The exp (expiration) claim is a Unix timestamp specifying when the token expires. Set it to a future time (e.g., Math.floor(Date.now()/1000) + 3600 for 1 hour from now). Servers should reject tokens past their expiry.
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