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JWT Security Scanner

Decode JWTs and check for critical security flaws (None alg, expired).

Free to use

Inspect a JWT locally

The token is decoded in this browser only. This tool does not verify the signature or prove that the token is trustworthy.

Security analysis

Waiting for a token…

Decoded payload


    




      
      
      

        
About JWT Security Scanner
Decode JWTs and check for critical security flaws (None alg, expired).

        
How to use this tool
  1. Enter the requested data or choose an upload.
  2. Check the file type and size limit before submitting.
  3. Review the result, then download or copy it.
  4. Keep the original and use the actions above to continue safely.
Read the full JWT Security Scanner guide →