Managing several routing rules manually started to feel clumsy once I needed different websites to use different connections. Changing the proxy every time was not practical, and exceptions alone were too basic for what I wanted. PAC files seem designed for this kind of situation, but I’ve only used simple configurations. Do they actually make day-to-day proxy management easier once the rules become more complex?
PAC files are most useful when routing rules are predictable and repeated often. They can remove a lot of manual switching, but they also introduce another configuration file that needs to be maintained. For two simple proxy profiles, an extension may be easier. When the rule is based on domains or patterns rather than manual choice, PAC becomes much more attractive because the browser can decide automatically.
PAC files started making sense to me when I had a small group of domains that needed one route while everything else could use another. I was tired of switching settings manually, so I reviewed the automatic configuration options alongside the normal
firefox proxy setup and moved the routing logic into a PAC file. After that, Firefox selected the route based on the address instead of requiring me to change profiles during the session. It was especially useful for repeated testing because the same rules applied every time I restarted the browser. I still keep PAC logic simple because complicated rules become harder to debug, but for stable routing patterns it saved me a lot of repetitive switching.