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Decode and inspect JSON Web Tokens. View header, payload claims, and expiration status.
A JWT is a compact, URL-safe token format with three Base64-encoded parts — header, payload, and signature — used for stateless authentication, API authorization, and secure information exchange between parties.
| Claim | Name | Description |
|---|---|---|
| iss | Issuer | Who issued the token |
| sub | Subject | User/entity identifier |
| aud | Audience | Intended recipient |
| exp | Expiration | Token expiry time |
| nbf | Not Before | Token activation time |
| iat | Issued At | Token creation time |
| jti | JWT ID | Unique token identifier |
No Verification: This tool decodes JWTs but cannot verify signatures. Always verify tokens server-side before trusting claims.
Not Encrypted: JWT payloads are only Base64-encoded, not encrypted. Anyone can decode them. Never store sensitive secrets in JWTs.
100% Client-Side: All decoding happens in your browser. Your tokens never leave your device.
Formula
JWT = Base64Url(header) . Base64Url(payload) . Base64Url(signature)header = JSON object with algorithm (alg) and token type (typ)
payload = JSON object with claims (iss, sub, exp, iat, custom data)
signature = HMAC-SHA256(base64(header) + "." + base64(payload), secret)
Worked Example
Decoding a JWT
Did you know? JWTs were introduced in 2010 via RFC 7519. They replaced opaque session tokens by embedding verifiable claims directly in the token — enabling stateless authentication across microservices without a central session store.
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