JWT Decoder API

Category: developer

Decode and inspect JSON Web Tokens (JWT). View header, payload, and verify expiration. Runs entirely in the browser.

Endpoint

N/A Browser API (atob)
No Server API

Response

Content-Type: N/A

This tool decodes JWTs in the browser using base64 decoding. No server-side API is available.

// Browser-only: uses atob() for base64 decoding

cURL Example

# No cURL equivalent — this tool runs in the browser

Code Samples

// JWT decoding in JavaScript
function decodeJwt(token) {
    const parts = token.split('.');
    const header = JSON.parse(atob(parts[0]));
    const payload = JSON.parse(atob(parts[1]));
    return { header, payload };
}

const decoded = decodeJwt('eyJhbG...');
console.log(decoded);
# JWT decoding in Python:
import jwt

decoded = jwt.decode(token, options={'verify_signature': False})
print(decoded)
// JWT decoding in Java (using jjwt):
// Jws<Claims> claims = Jwts.parser()
//     .setSigningKey(key)
//     .parseClaimsJws(token);
// System.out.println(claims.getBody());