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PEM証明書デコーダー

PEM形式の証明書をデコード。無料で登録不要。

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How to Use

  1. Paste your PEM-formatted certificate (including BEGIN/END lines)
  2. View the decoded certificate details instantly
  3. Check the validity dates, subject, and issuer information
  4. Verify Subject Alternative Names (SANs) for your domains

Common Use Cases

  • Verifying SSL certificate details before installation
  • Checking certificate expiration dates
  • Debugging TLS handshake and certificate chain issues
  • Inspecting certificate SANs for multi-domain coverage

Frequently Asked Questions

What information can I see from a PEM certificate?
You can see the subject (domain name), issuer (CA), validity dates, serial number, signature algorithm, public key type and size, and extensions like SANs and key usage.
Is it safe to paste my certificate here?
Yes. All decoding happens locally in your browser. Your certificate data is never sent to any server. Note: never paste private keys in any online tool.
What is the difference between PEM and DER format?
PEM is Base64-encoded text with header/footer lines, readable in any text editor. DER is the raw binary format. This tool only handles PEM format.