SSL certificate converter

The SSL converter changes certificates and private keys from one format to another without installing OpenSSL. Pick a mode (for example PEM → PFX), paste the text or choose the file, and download the result. All conversions run in your browser with JavaScript; certificates and keys are not uploaded anywhere.

How to use it

1. Choose the conversion at the top. Each mode also has its own page with details, linked below the tool.
2. Paste PEM text or choose a file. For PFX files, enter the password.
3. Press Convert (Create PFX in PEM → PFX mode) and download the files.

Modes

• PEM → DER: each PEM block (certificate, key or CSR) becomes a binary .der file, one object per file.
• DER → PEM: a binary certificate, key, CSR or DER .p7b becomes PEM text.
• PEM → PFX: certificate, chain and private key are bundled into a password-protected .pfx. The tool checks that the key matches the certificate and orders the chain. See PEM to PFX.
• PFX → PEM: a .pfx/.p12 is unpacked into fullchain.pem, cert.pem, chain.pem and privkey.pem. See PFX to PEM.
• P7B → PEM: certificates are extracted from a PKCS #7 bundle and put in chain order.
• CRT → PEM: a .crt or .cer file of either encoding becomes PEM.

Equivalent OpenSSL commands

# PEM → DER
openssl x509 -in cert.pem -outform DER -out cert.der
# PEM + key → PFX
openssl pkcs12 -export -out site.pfx -inkey privkey.pem -in cert.pem -certfile chain.pem
# PFX → PEM (add -legacy on OpenSSL 3 for old RC2-encrypted files)
openssl pkcs12 -in site.pfx -nodes -out all.pem
# P7B → PEM
openssl pkcs7 -print_certs -in certs.p7b -out certs.pem

Notes

• A PFX holds the private key: always set a strong password and delete copies you no longer need.
• privkey.pem from PFX → PEM is unencrypted, because web servers need it that way. Protect it with file permissions.
• DER can hold only one object per file; a chain needs several files or a PEM/P7B bundle.