Convert certificates and keys between PEM (Base64) and DER (binary) formats. Supports certificates, keys, and CSRs
Convert certificates and keys between PEM (Base64 text) and DER (binary) formats. Some servers and tools require one format; others require the other. Drop a file in, pick the target format, and download the converted result.
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Generate Certificate Signing Requests (CSR) for SSL/TLS certificates with RSA key pairs. Submit to CAs for certificate issuance
Decode and analyze PEM-encoded X.509 SSL/TLS certificates. View subject, issuer, validity, extensions, and fingerprints
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A Java keytool import rejects your .pem file because it wants binary DER, and you need to convert without installing OpenSSL.
Input
certificate.pem (Base64 text, "-----BEGIN CERTIFICATE-----")
Output
certificate.der (binary, 1,214 bytes) First bytes: 30 82 04 BA 30 82 03 A2 … (DER SEQUENCE) Direction is reversible: drop a .der back in to get PEM.
PEM and DER hold the same X.509 data: DER is the raw ASN.1 binary, and PEM is just that binary Base64-encoded and wrapped in `-----BEGIN-----` headers. Some tools (Java keystores, certain embedded stacks) accept only one form. The converter strips or adds the Base64 armor in your browser, no key material is uploaded.
Convert certificates and keys between PEM (Base64 text) and DER (binary) formats. Some servers and tools require one format; others require the other. Drop a file in, pick the target format, and download the converted result.
Convert PEM certificates to DER format for import into Java KeyStore (JKS) files.
Convert between formats when working with the Windows Certificate Manager, which often expects DER.
Convert certificates to the format required by embedded devices with limited format support.
PEM is Base64-encoded text wrapped in -----BEGIN/END----- markers. DER is the raw binary encoding. They contain the same data, just represented differently.
If you can open the file in a text editor and see -----BEGIN CERTIFICATE-----, it's PEM. If it's unreadable binary, it's DER.
This runs as client-side JavaScript. Keys, tokens, payloads, and other inputs never leave your device.