PEM / DER Converter
Convert PEM and DER (Base64) for certificates and keys
Safety note: Avoid pasting real private keys. All conversions run locally in your browser.
Input + output
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.
- Choose a PEM label when converting to PEM.
- 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.pemFAQ
Can I convert private keys?
Yes, but avoid pasting real private keys into online tools.
What if the PEM label is wrong?
Select the correct label for certificates, public keys, or private keys.
Does this tool store inputs?
No. Conversions run locally in your browser.