Paste a PEM-encoded certificate to see its subject, issuer, validity dates, and extensions decoded into readable JSON entirely client-side.
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Paste a PEM-encoded certificate to see its subject, issuer, validity dates, and extensions decoded into readable JSON entirely client-side. Common questions — like is it safe to paste sensitive data into this tool — are answered in the FAQ below.
Add your input to the workspace above, review the result, then copy or download it when it's ready. No account or installation is required.
Certificate Decoder runs in your browser, so the information you enter stays on your device instead of being uploaded to a server.
A few worked examples so you know what to expect before you paste in your own input.
Input
(paste your security input above)
Output
Paste a PEM-encoded certificate to see its subject, issuer, validity dates, and extensions decoded into readable JSON entirely client-side.
What PEM and DER actually are, when to convert between them, and how to decode an X.509 certificate's subject, issuer, and validity without OpenSSL memorization.
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