JWT Decoder — Decode & Inspect JWT Tokens Online Free
Free online JWT decoder to decode and inspect JSON Web Tokens without sending data anywhere. View header, payload, and signature information in a clean interface. Validate token structure and examine claims — 100% client-side.
100% client-side. Your JWT is never sent to any server. All decoding happens in your browser.
Example Tokens
Paste a JWT token to decode it
A JWT has the format xxxxx.yyyyy.zzzzz — three base64url parts separated by dots
JWT Structure
Header
Algorithm & token type
{ "alg": "HS256", "typ": "JWT" }Payload
Claims (data)
{ "sub": "1234", "exp": 1700000000 }Signature
Integrity verification
HMAC(base64(header) + '.' + base64(payload), secret)How to Use the JWT Decoder
Paste your JWT token
Copy your JWT token and paste it into the input field. The tool auto-detects the token structure.
Review the decoded parts
View the Header, Payload, and Signature sections decoded in a readable format.
Examine the claims
Check standard claims like Issuer, Subject, and Expiration alongside any custom claims.
Verify with a secret key
Optionally paste the secret or public key to verify the token signature client-side.
Frequently Asked Questions
JWT (JSON Web Token) is a compact, URL-safe token format for securely transmitting information as a JSON object.
No. All decoding happens entirely in your browser. Your token is never sent to any server.
The signature confirms the token has not been tampered with since it was signed by the issuer.
It means the token has no signature, which is a security risk. Never trust tokens using the 'none' algorithm.
Example Results
Try this sample token
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c
What you'll see
Header: {"alg":"HS256","typ":"JWT"} · Payload: {"sub":"1234567890","name":"John Doe","iat":1516239022}
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