DER naar PEM Converter

Converteer certificaten en sleutels in DER-binaire indeling naar PEM-tekstformaat. Deze tool verwerkt je bestanden lokaal in je browser voor maximale veiligheid en privacy.

Overview

DER to PEM conversion rewraps a binary X.509 certificate, private key, public key, or CSR as Base64 text with the familiar BEGIN/END headers that Apache, Nginx, and most TLS toolchains expect. This converter runs the entire operation inside your browser using the Web Crypto and File APIs — the binary data is read locally, encoded to Base64, and returned to you without ever touching a server. Because certificate files often contain private key material, keeping the conversion offline is not a convenience feature; it is a security requirement.

Common Use Cases

  • Web Server Deployment — Administrators deploying TLS certificates received in DER/CER format from an enterprise CA need PEM output before configuring Apache or Nginx virtual hosts.
  • OpenSSL Compatibility — Developers working with OpenSSL-based toolchains use this to convert binary .cer or .crt files into PEM so they can inspect, chain, or sign them with standard CLI commands.
  • Private Key Format Migration — Security engineers migrating private keys between systems that use different encoding conventions convert DER-format keys to PEM without risking exposure to an online service.
  • CSR Submission — Teams that generate certificate signing requests programmatically in DER binary form use this to produce the PEM text required by most public CA submission portals.
  • Certificate Inspection — sysadmins who receive opaque binary .der files use this to produce readable PEM output they can paste into a certificate viewer or diff against an expected fingerprint.

How It Works
1

Upload DER File

Upload your binary DER-formatted certificate, key, or CSR file (.der, .cer, .crt extensions).

2

Automatic Conversion

The tool reads the binary data and converts it to Base64-encoded PEM format with proper BEGIN/END headers.

3

Download or Copy PEM

Download the converted PEM file or copy the text content to use in web servers, applications, or for viewing.

Frequently Asked Questions

Why convert DER to PEM format?
PEM format is more widely supported, human-readable, and easier to work with in text editors. Most web servers and applications prefer PEM format for certificates and keys.

How can I tell if a file is in DER format?
DER files are binary and appear as unreadable characters when opened in text editors. They often have .der, .cer, or .crt extensions and are typically smaller than PEM files.

Will the conversion change the certificate content?
No, DER to PEM conversion only changes the encoding format from binary to Base64 text. All certificate information, validity, and cryptographic properties remain unchanged.

Can I convert any type of DER file?
Yes, the tool can convert DER-formatted certificates, private keys, public keys, and certificate signing requests (CSRs) to PEM format.

Is it safe to upload my certificates?
Yes, all conversion happens locally in your browser. Your certificate files are processed entirely on your device and never uploaded to external servers.

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