Bartel Media JWTDebugger
Security tool · 100% client-side

The Free JWT Debugger

Decode and inspect JSON Web Tokens instantly in your browser. View the header, payload and signature — all parsed and pretty-printed. Your tokens never leave your device.

Decode your JWT


        

        

          
          

        

        

          
          

        

      

    

  







  01 — The basics
  
What is a JSON Web Token?

  
A JSON Web Token (JWT) is a compact, self-contained way to securely transmit information between two parties as a JSON object. JWTs are widely used for authentication and authorization in modern web applications and APIs — you've almost certainly passed one in an Authorization: Bearer header.

  
A JWT consists of three Base64URL-encoded segments separated by dots: the Header (algorithm and token type), the Payload (claims — data like user ID, roles, expiry), and the Signature (used to verify the token hasn't been tampered with). Only the third part is actually secret — the first two are just encoded, not encrypted.

  
eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9   ← Header
.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ  ← Payload
.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c  ← Signature




        
    



  02 — How to use it
  
How to use this JWT Debugger

  
    
        
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    Paste your JWT
    
        
    Copy a JWT from your browser DevTools, API response, or auth header and paste it into the input field above.
    
      
    
    
    2. 
        
  2. 
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    Inspect the decoded output
    
        
    The Header, Payload and Signature are instantly decoded and displayed in separate panels. The Payload is pretty-printed JSON.
    
      
    
    
    3. 
        
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    Check the expiry
    
        
    If your token contains an exp claim, the tool shows whether the token is still valid or has expired.
    
      
    
    
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    Debug with confidence
    
        
    Everything runs in your browser — nothing is transmitted to any server. Safe to use with real tokens during development.
    
      
    
    
    5. 
      







  03 — FAQ
  
Frequently asked questions

  

        

      
        What is a JWT?
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A JSON Web Token (JWT) is a compact, URL-safe token used for authentication and information exchange between parties.

    

        

      
        Is this safe to use with real tokens?
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Yes. Decoding happens entirely in your browser. No data is sent to any server.

    

        

      
        Can it verify signatures?
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This tool decodes and displays the token structure. Signature verification requires the secret key, which we intentionally do not handle.

    

        

      
        What are the three parts of a JWT?
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A JWT has three parts: Header (algorithm info), Payload (claims/data), and Signature (verification hash).