A local proxy app that forwards requests to a parent proxy with automatic autorization. Preproxy is basically an improved, sandboxed, Mac App Store-enabled version of Authoxy. I made it because Authoxy has been abandoned for quite some time and has started having problems since macOS Sierra came out.

Download Preproxy on Mac App Store

Most open source apps are incapable of reading proxy password saved in System Preferences. Hardcoding the password in export http_proxy=... is no good either. Preproxy accepts proxy requests on localhost and forwards them to the given remote proxy, automatically taking care of proxy authorization using the credentials stored in Keychain.

NTLM and Kerberos authentication methods are supported. Even those apps that do read proxy credentials from macOS keychain often don’t care to support advanced methods like Kerberos; with Preproxy it is now possible to have any app in the system to authorize at the proxy uniformly and without saving password at all. Kerberos is main authorization method in Windows Active Directory domains, so most corporate network proxies should already support it.

Preproxy also supports Proxy Auto-Configuration scripts that are commonly used in Windows networks. This allows command line apps to automatically use the latest configuration provided by network administrators.

Support links:

  • Create a Support Ticket to report a bug, suggest a feature or ask a question (ignore account creation email if you don’t want to monitor ticket status).

  • Check Knowledge Base for tips on using the app.

  • Preproxy Privacy Policy as required by Mac App Store.

Preproxy 1.5 NTLM Screenshot

Preproxy 1.5 Kerberos Screenshot

Preproxy 1.5 Exceptions Screenshot

New changes:


  • Gracefully handle the case when parent proxy unexpectedly drops connection mid auth.


  • An option to bypass parent proxy for certain IP/domains to have uniform configuration between command-line and GUI apps.
  • Allow longer Kerberos authentication tokens (“Malformed message” error)
  • Fixed sporadic “Host not found” DNS failures
  • Listen on IPv6 port too if available
  • Recent requests UI improved slightly


  • Try direct connection if remote proxy is unavailable (a case of MacBook carried from office to home and back)


  • Proxy Auto-Configuration support (w/o SOCKS)


  • Recent requests UI
  • Error log for failed requests
  • Web servers running on localhost will be always connected directly
  • NOTE: Upgrading to High Sierra turns autostart at login off for unknown reason. You will have to open GUI and click the checkbox to reenable it.


  • Kerberos support
  • NTLM support
  • Latest request result for easier diagnostics