Web Tools
JWT Builder
Create and encode JWT tokens with HS256 signing or unsigned (alg: none). Configure payload, secret key, and algorithm. Color-coded token output with header, payload, and signature parts. Runs entirely in your browser — your data never leaves your machine.
jwt json-web-token encoder authentication security
Published May 28, 2026
All interactive tools run entirely in your browser. Your data never leaves your device.
How It Works
Enter your payload as JSON, choose an algorithm (HS256 or none), and optionally set a secret key. The tool encodes the header and payload using base64url, then signs the token using HMAC-SHA256 via the Web Crypto API. The resulting JWT is displayed with color-coded parts: header (red), payload (purple), and signature (blue).
Features
- Two algorithms: HS256 (HMAC-SHA256 signing) and none (unsigned)
- Live encoding: token updates as you type
- Color-coded output: header, payload, and signature in distinct colors
- 4 example payloads: basic, API auth, service token, custom claims
- Web Crypto signing: secure HS256 signatures using the browser’s native crypto API
- Complements JWT Decoder: build tokens here, verify them in the decoder tool
- Private: runs entirely in the browser — no data transmitted
Use Cases
- Building test JWTs for API development
- Creating example tokens for documentation
- Understanding JWT structure and encoding
- Testing JWT validation in your applications
- Generating tokens for local development