X.509 Certificate Decoder

Decode X.509 / PEM certificates.

PEM certificate
Decoded 

  







  

    
Related Encoder / Decoder tools

    

        
          
Base64 String

          
Encode/decode Base64 text (UTF-8 safe).

        
          
Base64 Image

          
Encode/decode Base64 images and data URIs.

        
          
URL Encode / Decode

          
Percent-encode and decode URLs.

        
          
HTML Entity Encode / Decode

          
Encode/decode HTML entities.

        
          
Backslash Escape / Unescape

          
Escape/unescape backslash sequences.

    

  




  
About the X.509 Certificate Decoder

  

      

        
What does the X.509 Certificate Decoder do?

        
Decode X.509 / PEM certificates. GeekTool runs the X.509 Certificate Decoder entirely in your browser — input never leaves your device.

      

      

        
Is the X.509 Certificate Decoder free?

        
Yes. The X.509 Certificate Decoder is part of GeekTool, a free suite of 50+ developer utilities. No sign-up, no ads inside the tool, no quotas.

      

      

        
Does the X.509 Certificate Decoder send my data to a server?

        
No. All processing is client-side JavaScript. Your input stays in your browser tab — we never see it.