A PFX file is a digital certificate that's used to determine whether a device like a computer or Web server is authentic, that is, whether it is what it says it is. You can open a PFX file with the native program Microsoft Certificate Manager. This program is already installed on Windows computers, so you won't have to download anything new to use it.
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Click "Start" in Windows.
Type "certmgr.msc" into the search box and press "Enter" to bring it up.
Double-click on the PFX file in the Certificate Manager to open it.