Free Online JWT Decoder & Encoder
Securely inspect, decode, and generate JSON Web Tokens in seconds. This tool keeps the workflow simple: decode or encode on the left, supporting content below, and the sidebar on the left for popular and related tools.
Instant decoding
Paste a token to view its header, payload, and signature right away.
Generate signed tokens
Build a new JWT from your own header, payload, and secret in one click.
Modern algorithms
Works with common standards like HS256 and RS256 for signing and checks.
Private by design
Everything runs in your browser, so your tokens and secrets never leave your device.
How it works
- Pick Decode to inspect a token, or Encode to build a new one.
- In Decode mode, paste your JWT and click Decode Token.
- In Encode mode, fill in the header, payload, and secret, then click Encode JWT.
- Read the decoded parts or the generated token in the result panel on the right.
Best practices
- Keep your signing secret private and never share it publicly.
- Use valid JSON for both the header and payload when encoding.
- Verify the signature with the correct secret before trusting a token.
- Avoid storing sensitive data inside the payload, as it is readable.
- Set short expiry times so tokens stay valid only as long as needed.
- Use this tool for development and debugging, not as a key store.
Frequently asked questions
Is this JWT tool free to use?
Yes. This JWT Decoder & Encoder is completely free and doesn't require any sign-up, subscription, or payment.
Are my tokens or secrets stored on your server?
No. All operations run client-side using JavaScript. Your tokens and secrets never leave your device.
Can I validate a JWT's signature here?
Yes. By entering the token and the matching secret key or public key, the tool can verify whether the signature is valid.
Which algorithms does this tool support?
The tool supports the most common algorithms, including HS256 (HMAC with SHA-256) and RS256 (RSA signature with SHA-256).
Can I edit the payload and generate a new token?
Yes. You can modify the JSON payload in the editor, and the encoder will generate a new signed JWT for you.
What happens if my JWT is invalid?
The tool displays an error message if the token is malformed or if signature verification fails due to an incorrect secret.
Why are JWTs Base64 encoded?
Base64 encoding makes the token URL-safe, so it can be passed in HTTP headers or query parameters without breaking.
Can I use this for production tokens?
The tool is secure since it runs locally, but we recommend using it mainly for debugging and development testing.
Does the tool support nested JSON in the payload?
Yes. As long as the payload is a valid JSON object, you can include nested objects and arrays as claims.
Do I need an internet connection to use this?
You need to load the page first, but since the logic is client-side, decoding and encoding happen right in your browser.
Need more security tools? Inspect the individual parts of a token with the Base64 Encoder & Decoder tool, or check data integrity with the SHA-256 Hash Generator tool.