What is CER? What Opens a CER? File Format List from WhatIs.com

File Extension

CER File Format

Certificate file (MIME x-x509-ca-cert)

CER file format icon

CER is a file extension for an SSL certificate file format used by Web servers to help verify the identity and security of the site in question. SSL certificates are provided by a third-party security certificate authority such as VeriSign, GlobalSign or Thawte.

MIME type: application/x-x509-ca-cert, application/pkix-cert, application/keychain_access


Learn more about CER files:

Brien Posey tells 'How to set up an SSL certificate to encrypt OWA and ActiveSync traffic'.

Get answers to certificate-related questions at IT Knowledge Exchange.

Visit the VeriSign, GlobalSign or Thawte webpage.

This was last updated in August 2010
Editorial Director Margaret Rouse

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