CERTINITE · FREE SSL TOOLS

PEM to DER / CRT Certificate Converter

Convert an X.509 certificate between PEM and binary DER/CRT entirely in your browser. No uploads, private keys or account required.

  • No signup required
  • Full results, always free
  • Built for IT & DevOps

Use this tool free, without an account

Enable JavaScript to use the interactive tool. Instructions and troubleshooting guidance are available below.

How it works

Choose PEM to DER and paste a certificate, or choose DER to PEM and select a local binary certificate file. The tool validates the X.509 structure before creating a downloadable file.

What does this tool check?

  • PEM certificate to binary DER (.crt)
  • Binary DER certificate to PEM (.pem)
  • Strict single-certificate input validation
  • Local processing with no certificate upload

Common issues & how to fix them

A .crt file is not always DER

The extension is only a filename convention. Open the file in a text editor: BEGIN CERTIFICATE indicates PEM. A binary certificate typically uses DER.

Private key or PFX supplied

This converter handles public certificates only. PFX containers include additional structures and may contain private keys. Use a trusted local certificate management tool for those operations.

Conversion did not fix a trust error

PEM and DER store the same certificate bytes in different encodings. Converting cannot change validity, names, issuer or trust.

Frequently asked questions

Can this create a PFX file?

No. This release deliberately handles only public certificate PEM/DER conversions. It never requests or processes a private key.

Is my certificate uploaded?

No. Parsing, conversion and file creation run in a sandboxed browser frame that cannot make network requests.

Will conversion alter the certificate?

No. The DER certificate bytes are preserved. PEM adds base64 encoding and a header/footer around those bytes.

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