FoxyProxy Standard by Eric Jung, erosman

FoxyProxy is owned and developed consistently by the same few people since 2006. It has never been sold and never will.

WHAT IS IT?
FoxyProxy is a Firefox and Chrome extension that switches an internet connection across one or more proxy servers. Proxies can be switched by:

1. point-and-click of colored icons in a popup menu
2. URL - define URL patterns with wildcards or regular expressions
3. browser tab - set individual proxies per tab!
4. Firefox container or Private Browsing windows - define different proxies for each container

SOME FEATURES
- Automatically switch proxy by: browser tab, URL patterns, firefox container, private browsing window, or manually select from a drop-down list
- Customize colors and country flags to make it easy to see which proxy is in use
- Import/Export all of your settings, or just URL patterns, to share with others. Optionally synchronize proxy settings with your other Firefox instances when you use Firefox Sync.
- Keyboard shortcuts to quickly switch proxies and perform other actions
- Turn WebRTC on/off to further limit discovery of your IP address
- Quick-Add to quickly add new URL patterns to proxy settings
- Globally exclude any website from all proxying
- Built-in pattern tester to test and debug your URL patterns
- Advanced logging shows you which proxies were used and when so you can debug problems
- Extensive built-in help

PERMISSIONS
- downloads: Required to export the extension settings to a file. Users can import that file to other Chrome/Firefox instances, or share it with colleagues, in order to keep the same settings. It can also be backed up and used later.
- proxy: The core function of the extension is to allow users to set the proxy server used by the browser.
- storage: Required to store proxy server settings (hostname, port, username, and which proxy server is enabled by the user)
- tabs: Required so that users can set separate proxies to use per tab. It is also needed for "QuickAdd" to quickly add a URL pattern that applies to the current/active tab. It is also used to open a URL to getfoxyproxy.org where there is online help.
- webRequest: Required to authenticate with proxy servers via webRequest.onAuthRequired
- webRequestAuthProvider: Required to authenticate with proxies servers via webRequest.onAuthRequired
- browsingData: Required so the extension can delete cookies, indexedDB, and localStorage when requested by the user on the Options page (Delete Browsing Data button)
- privacy: Required so the extension can call browser.privacy.network.webRTCIPHandlingPolicy to turn on/off webRTC in Chrome (Limit WebRTC checkbox in Options page)
- host permission: Required to proxy all webRequests and provide proxy server authentication. all_urls is used because users may choose to load any/all URLs through proxy servers (chrome.webRequest.onAuthRequired and chrome.webRequest.onAuthRequired.addListener) . Required to proxy all webRequests and provide proxy server authentication. Also needed to get accounts details from FoxyProxy servers, if requested by the user with the Import FoxyProxy Account on the Import tab.

No remote code is used in this extension.

Open source software
You can view the code yourself by unzipping the downloaded file or:

https://github.com/foxyproxy/browser-extension