Open PAC File
PAC extension files can be used in various applications and formats, some of them described below.
Proxy Auto-Config File
A PAC file extension, in this particular case, is a configuration file used by web browsers to select a suitable proxy server.
The PAC contains one or more JavaScript functions with one called FindProxyForURL, which defines the rules for choosing a proxy server based on a given URL.
But what is a proxy?
A proxy server is a server application that acts as an intermediary between a client requesting a resource and the server providing that resource.
PAC files are used to control and load balance Internet traffic, especially in corporate environments.
PAC files are activated in web browsers by entering the URL of the PAC file in the proxy connection settings, or by using the Web Proxy Auto-Discovery (WPAD) protocol.
When run, a PAC file returns a string containing one or more proxy server URLs.
PAC files are usually hosted on a web server and should have a PAC file name extension, filename.pac.
Since PAC files contain the configuration in plain text, it is possible to use a text editor such as Geany or Apple TextEdit to view or modify the files.
PAC Subtitles File
Another quite interesting application for a PAC file is as a subtitle format, being a proprietary format created by Screen Subtitling Systems.
The PAC extension file is used to sync closed captions with a video timeline, and can be edited with subtitle editing software such as EZTitles and converted to more standard formats, including SRT and SUB.
SBStudio II Song File
In this section, PAC file is a song format, called PAC or package file, used by SBStudio.
SBStudio is a graphical development environment used to create and test StreamBase applications.
The PAC file is made up of data blocks that store song information and audio data.
Software to open and work with a PAC file
Due to the great difference between the types of formats associated with the PAC extension, it is necessary to keep in mind the format of it, in order to use the most suitable software package.