PEM / DER Converter

Convert PEM and DER (Base64) for certificates and keys

Safety note: Avoid pasting real private keys unless your approved workflow allows it. Review labels and structure before using converted output.

Input + outputRewrap the same DER bytes as PEM text or return a PEM body as DER Base64; this does not change the ASN.1 structure

Input (PEM or DER Base64)

Output

Input format

Output format

PEM label

For unlabeled DER Base64, this applies a text label only. It does not prove the label matches the encoded object.

What Is PEM vs. DER?

PEM is a Base64-encoded format with header and footer lines (for example, BEGIN CERTIFICATE). DER is the binary encoding of the same data. This converter outputs DER as Base64 to keep it copy-friendly.

How to Convert PEM and DER

Paste a PEM block or DER Base64 string.
Select the desired output format.
For unlabeled DER Base64, choose a PEM label only after identifying the encoded object.
Click Convert and copy the output.

Do This Locally (CLI)

# Convert PEM to DER (binary)
openssl x509 -in cert.pem -outform der -out cert.der # Convert DER to PEM
openssl x509 -inform der -in cert.der -out cert.pem

FAQ

Can I convert private keys?

This tool can change the wrapping of the same encoded key, but it does not convert PKCS#1 to PKCS#8 or add or remove encryption. Avoid pasting real private keys.

What if the PEM label is wrong?

A different label does not transform the encoded object. Identify the object first, then apply the matching certificate, request, public-key, or private-key label.

Does this tool store inputs?

The converter accepts supported PEM and DER representations and returns the selected format with its label and encoding intact.