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SSL Certificate Format Converter

Convert SSL/TLS certificates between PEM, DER, Base64 and Hex, and read the certificate details. Nothing leaves your browser.

Waiting for input

Converted and parsed locally with a built-in DER / ASN.1 reader — no server calls, so private keys and certificates never leave your machine. The converter handles single certificates; it does not split PKCS#7 bundles or decrypt PKCS#12 files.

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What Is SSL Certificate Converter?

The SSL Certificate Format Converter converts certificates between PEM, DER (Base64), DER (Hex) and the .crt / .cer file extensions, then decodes the X.509 fields so you can read the subject, issuer, validity window, key size and CA status without installing OpenSSL.

Who Uses the SSL Certificate Converter?

System administrators and developers use it when a server or load balancer rejects a certificate in the wrong encoding, when converting a .der to .pem for Nginx or Apache, or when auditing an unexpected certificate during an incident.

How to Use the SSL Certificate Converter

  1. Paste the certificate as PEM text, Base64 DER, or Hex DER - or choose a .pem, .cer, .crt or .der file.
  2. Review the detected format and the decoded subject, issuer, dates, key size and CA flag.
  3. Pick PEM, DER (Base64) or DER (Hex) to produce the converted output.
  4. Copy the result or download it with a matching filename.

Why Choose Our SSL Certificate Converter?

  • Converts PEM, Base64 DER and Hex DER, and reads back every format it produces
  • Decodes subject, issuer, serial, version, validity dates, key size and CA status
  • Flags expired certificates and those expiring within 30 days
  • Runs entirely in the browser with a built-in DER / ASN.1 reader - no uploads, no server calls

Try the SSL Certificate Converter above — it is free, fast, and works on any device. Bookmark this page to return whenever you need it.