JWT Builder & Signer

About JWT Builder & Signer

Build, sign, and verify JSON Web Tokens (JWT) entirely in your browser. Choose HMAC algorithm (HS256, HS384, or HS512), set any standard or custom claims, enter a secret key, and get a signed JWT instantly. Switch to Verify mode to validate any JWT signature. Uses the Web Crypto API — your secret never leaves your device.

How to Use JWT Builder & Signer

Create, sign, and verify secure JSON Web Tokens using HMAC algorithms directly in your browser.

1. 1

   Select your HMAC signing algorithm

   Choose between HS256, HS384, or HS512 from the algorithm dropdown menu to define the cryptographic hash function.

2. 2

   Configure your standard and custom claims

   Enter the JSON payload including standard claims like sub or exp, or add any custom data fields required for your token.

3. 3

   Enter your secure secret key

   Input the secret string used to sign the token; the Web Crypto API ensures this key never leaves your local device.

4. 4

   Generate and copy the signed JWT

   The tool instantly builds and signs the token. Copy the resulting three-part encoded string for use in your application.

5. 5

   Verify an existing JWT signature

   Switch to Verify mode and paste a token to validate that its signature matches the provided secret key.

Estimated time: PT1M

Frequently Asked Questions

Related Articles

JWT Builder & Signer: Create, Sign, and Verify JWTs Online

Build, sign, and verify JSON Web Tokens using HS256, HS384, or HS512. Secure browser-based JWT generation with custom claims and Web Crypto API protection.