JWT Decoder – Decode & Inspect JSON Web Tokens Online
Decode and extract information from JSON Web Tokens (JWT) client-side without compromising security. All conversions and calculations happen locally inside your browser memory — no data is ever transmitted over network connections.
JWT Decoder
⚡ How JWT Decoder Works
Paste Encoded JWT
Insert your Bearer token string into the decoder window.
Auto-Split Token Sections
The tool parses the 3 Base64URL-encoded segments (Header, Payload, Signature).
Inspect Claims & Expiration
Review public claims, user permissions, issuer info, and expiration timestamps.
💻 Code Example & Output
Decodes Base64URL encoded header and payload segments into legible JSON objects without exposing secret keys.
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c// Header
{
"alg": "HS256",
"typ": "JWT"
}
// Payload Claims
{
"sub": "1234567890",
"name": "John Doe",
"iat": 1516239022
}🎯 Key Use Cases for JWT Decoder
Debugging OAuth2 & Auth0 Flows
Inspect token scopes, client IDs, and user roles to resolve authorization failures in web applications.
Checking Token Expiration (exp claim)
Verify exact timestamp values for exp, iat, and nbf claims to troubleshoot session timeouts.
Frontend State Inspection
Extract user metadata stored inside JWT claims directly in client applications without server calls.
Security Audit & Compliance
Ensure sensitive passwords or private credentials are not mistakenly embedded inside public token payloads.
💡 Frequently Asked Questions
Q: Is my secret key or token exposed when decoding here?
No! Decoding is 100% client-side using JavaScript string splitting and window.atob Base64 decoding. Your token is never transmitted over HTTP.
Q: Can I verify the JWT signature here?
Decoding shows header and payload content. Signature verification requires the secret key or public RSA key provided by your authentication server.
Q: Are JWT tokens encrypted?
Most JWTs are signed and encoded, not encrypted. Anyone with the token string can read header and payload claims.
Q: What are standard claims inside a JWT?
Standard claims include iss (issuer), sub (subject/user ID), exp (expiration timestamp), iat (issued at), and aud (audience).
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