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.
Click "Start" in Windows.
Type "certmgr.msc" into the search box and press "Enter" to bring it up.
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Double-click on the PFX file in the Certificate Manager to open it.