How to Convert a .txt to a .cer Certificate File (PEM, DER, and the Extension Confusion Explained)

• 21 June 2026
• by: Aisha Khan
• in: SSL Certificates
• Tags: cer file, certificate formats, DER, OpenSSL, PEM, SSL certificates
• note: no comments

Learn how to convert a .txt to a .cer certificate file. Understand PEM vs DER encoding, certificate extensions, and openssl conversion commands the right way.

Read More »