For one-off PAC files, your browser is a basic extractor.
pac-resolver (npm package) + custom AST walker.
Several commercial and open-source tools package extraction into a user-friendly interface. .pac File Extractor
The primary task: scan the JavaScript AST (Abstract Syntax Tree) to extract every hostname, domain pattern (using shExpMatch ), IP subnet, and time-based rule.
This pattern can be extended to extract isInNet IP ranges, dnsDomainIs entries, and all proxy strings. For one-off PAC files, your browser is a basic extractor
Some advanced extractors can simulate FindProxyForURL() calls against a list of test URLs to validate logic without deploying the PAC file.
# Attempt to execute function for given test URLs ctx = execjs.compile(pac_code) test_urls = ["http://google.com", "http://internal.company.com", "http://blocked-site.com"] results = {} for url in test_urls: host = url.split('/')[2] try: proxy_result = ctx.call("FindProxyForURL", url, host) results[url] = proxy_result except: results[url] = "Execution error" The primary task: scan the JavaScript AST (Abstract
const fs = require('fs'); const acorn = require('acorn'); const walk = require('acorn-walk');