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Gas Mask

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Gas Mask is simple hosts file manager for macOS. It allows editing of host files and switching between them.

System requirements

Runs on Lion, Mountain Lion, Mavericks, Yosemite, El Capitan, Sierra, High Sierra and Mojave.


Download latest version (0.8.6)


Drag the application from Downloads into Applications folder. The first time you launch it, it will ask for your password, because it needs escalated privilege to modify your /etc/hosts file.

How it works

Gas Mask monitors /etc/hosts system file and updates it with your activated hosts file.

Gas Mask stores your custom hosts files in ~/Library/Gas Mask directory.

Application log can be found in ~/Library/Logs/Gas Mask.log. Its worth having a look for errors in there when posting an issue.

User Guide

Gas Mask usually operates in the background. It adds a tray icon, where you can access the main editor window and quickly switch between hosts files.

The main editor consists of three parts: Toolbar, a list of your hosts files on the left, and file editor on the right. Initially you will have a single file called Original file under Local, which is a copy of your original /etc/hosts file.

To add new files, click Create(+) button in the toolbar and select the type of file (Local, Remote or Combined).

To remove a file, select it and press the Remove button in toolbar.

To activate a file, select it and press Activate button in toolbar, or select it from tray icon when the editor is hidden. Gas Mask will update the /etc/hosts file with the currently activated file. The active file is marked with a check in the editor list, and can also be displayed next to Gas Mask tray icon (Preferences > Show Host File Name in Status Bar)

Local files

These are ordinary local files that you can edit.

Remote files

These are files that Gas Mask downloads and synchronizes from remote URLs. You can adjust how often they sould update in Preferences, or force an update from tray icon. You cannot edit these files, as they are be overwriten by update.

  • NOTE the current version has a bug that allows remote files only from http:// sources (no https://)

Combined files

This is where Gas Mask shines compared to other hosts managers for MacOS. A combined file doesn't contain hosts entries, but a list of local and remote files.

Where to find hosts files

A great source of curated hosts files can be found at

Building Gas Mask

Gas Mask can be built with XCode 10.1