Encoded Token
HEADER: ALGORITHM & TOKEN TYPE
PAYLOAD: DATA
JSON Web Tokens (JWT) are an open, industry-standard RFC 7519 method for securely representing claims between two parties. JWTs are ubiquitous in OAuth 2.0, OpenID Connect, and modern stateless REST authentication. Our client-side JWT decoder decodes and formats token headers and payloads in real time.
A standard JWT consists of three parts separated by periods (.): header.payload.signature
• Header: Specifies the cryptographic algorithm (e.g., HS256, RS256) and token type.
• Payload: Contains claims such as issuer (iss), expiration timestamp (exp), subject (sub), and user roles.
• Signature: Cryptographic hash ensuring the token has not been tampered with.
Remember that Base64Url encoding is NOT encryption. Anyone who intercepts a JWT can decode and inspect its payload claims. Never store unencrypted credit card numbers, passwords, or sensitive PII inside a JWT payload.
Because our decoder operates 100% client-side in your browser, your auth tokens and API secrets are never shared across the internet.
• exp (Expiration Time): Unix timestamp after which the token is invalid.
• nbf (Not Before): Timestamp before which the token must not be accepted.
• iat (Issued At): Creation timestamp.
Decoding inspects the Base64Url header and payload claims. Signature verification requires validating against the server's private key or HMAC secret.
Yes! All decoding happens purely inside your browser memory using local JavaScript. No data is sent over the network. However, we always recommend testing with staging/sandbox tokens as a best practice.
HS256 uses a shared symmetric secret key, while RS256 uses an asymmetric public/private key pair.
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