JWT Encoder
Generate signed JSON Web Tokens with HS256, HS384, or HS512. Set custom header and payload, provide a secret, and copy the encoded JWT.
JWT Encoder
How it works
1. Base64URL-encode the header JSON and payload JSON separately.
2. Concatenate them as header.payload.
3. Sign that string using HMAC with your chosen SHA algorithm and secret.
4. Base64URL-encode the signature and append as header.payload.signature.
⚠ For development and testing only. Never expose real secrets in a browser tool.
How JWT signing works
HMAC-based JWT signing combines the Base64url-encoded header and payload with a secret key to produce a signature. The three parts are joined with dots to form the final token.
Security warning
Never use real production secrets in browser-based tools. This encoder is intended for development, testing, and learning only.
How to use
- Choose an algorithm (HS256, HS384, or HS512).
- Edit the payload JSON — add any claims you need.
- Enter a secret key.
- Click Generate JWT and copy the result.
Signing runs in your browser using the Web Crypto API — no data is sent to any server.
Frequently Asked Questions
- Which algorithms are supported?
- HS256, HS384, and HS512 (HMAC-SHA). RS256 and other asymmetric algorithms are not supported in this browser tool.
- Is this safe to use with production secrets?
- No. Never enter production secrets into any browser tool. Use this for development and testing only.