JWT Decoder Online
High-security JWT decoder online. Inspect JSON Web Tokens instantly with client-side decoding.
JWT Decoding & Security
Our online JWT decoder runs entirely in your browser. Tokens are base64-encoded, not encrypted. Never store sensitive data like passwords or secrets in a JWT payload.
Built With Care
“JWT decoding uses base64url conversion, not decryption. This tool shows the raw token contents without verifying signatures, so decoded payloads should be treated as untrusted data.”
JWT Decoder
Paste a JWT and read its header and payload as formatted, readable JSON, with standard claims like iss, aud, sub, iat, and exp shown at a glance. This decoder focuses on quick claim inspection — algorithm, expiration, and issuer checks — without signature verification, which requires the signing key.
- 1Copy your JSON Web Token (JWT) from your application or environment.
- 2Paste the encoded string into the text area above.
- 3Click 'Decode JWT' to extract the header and payload data.
- 4Review the decoded JSON for claims, timestamps, and user data.
- 5Use the copy buttons to save the decoded components to your clipboard.
- Client-side decoding: Instant results with no server round-trips.
- Real-time Analysis: Instantly identify token algorithms and data types.
- Claim Detection: Easily read standard claims like sub, iat, and exp.
- No Server Storage: Tokens are decoded in your browser and are not stored or sent to our servers.
- Pro UI: Organized view of Header and Payload for better readability.
JWT Decoder Specs
Limits
- Decoding only — no signature verification
- Standard 3-part JWT (header.payload.signature)
Formats
- Output: header + payload JSON, signature hex
Defaults
- Empty input
How it works
- atob for base64url decode
Honest caveats
- Do not paste production tokens — anything in the input is shown verbatim
- Expired or invalid tokens still decode (just don't trust the claims)
Real Ways People Use This
API Debugging
Inspect JWTs returned by authentication endpoints to verify claims, expiration times, and user data.
Token Validation
Quickly check if a JWT contains the expected issuer, audience, and subject claims before testing authorization logic.
Security Auditing
Review JWT payloads for sensitive data exposure or misconfigured claims in production tokens.
- Decoding a JWT does not verify signature validity; treat unverified payloads as untrusted.
- Tokens may include sensitive claims, so avoid sharing decoded payloads without redaction.
- Expiration (`exp`) and issuer/audience checks must be enforced in your backend auth logic.
- 1Paste token and decode header/payload for quick inspection.
- 2Verify expected claims (`iss`, `aud`, `sub`, `exp`) against your auth policy.
- 3Perform signature verification with correct key/algorithm in your backend or auth service.