Convert between PEM, DER, and PFX/P12 formats online. Free PEM to DER converter.
The PEM to DER Converter converts certificate and key files between common formats. PEM is base64-encoded with -----BEGIN/END----- lines and is used in many Unix configs (e.g. nginx, Apache). DER is the binary form of the same data. PFX (PKCS#12) or P12 is a container that can hold a certificate and private key together, often used on Windows or for import/export. Use this tool when you receive a cert in one format but your server or application expects another, when you need to bundle cert and key into a PFX for a Windows server or Java keystore, or when you want to inspect or normalize a file. Conversion is typically done in-browser so sensitive keys are not uploaded. Some tools also support converting to/from other formats (e.g. CER, P7B).
Some systems (e.g. Java, certain APIs) expect DER or binary. PEM is more common in Linux and config files.
PKCS#12: a format that can contain both certificate and private key, often password-protected. Used for import/export.
Yes. PEM and DER are equivalent; conversion does not change the cert or key, only the encoding.
Yes. Private keys can be PEM or DER. Use the same tool or a dedicated key converter; keep keys secure.
If the tool runs in-browser, data stays on your device. Always confirm before pasting private keys.