Pactester

Pactester is a handy, lightweight and portable software solution that was designed to provide you with a way of testing Proxy Auto Configuration (PAC) files without spending too much time and without over-complicating things.

PAC files are documents that are used by Internet browsers to determine the appropriate proxy for a URL. Since the PAC file evaluation mechanism is generated internally, within the Internet browser and can't actually be accessed from outside of this environment, the only way to tell which proxy will your browser use for any specific URL is by manually inspecting the PAC document.

However, manual inspection rarely scales very well. In this situation, using a dedicated third-party software solution such as Pactester usually resolves this problem. This application makes use of a JavaScript interpreter and Netscape/Mozilla APIs to analyze the PAC files in use and as a result automates the whole process, making it easy for you to determine the proxy being used with any specific URL.

This application is portable, meaning that you don't need to install it on your computer in order to use it. Just unpack it and call the executable from a Command Prompt (since it doesn't feature a GUI, but only a CLI).