Gas Mask

Gas Mask provides a graphical interface for managing the macOS `/etc/hosts` file. It monitors the system hosts file and replaces its contents with the currently selected custom file, which it stores in `~/Library/Gas Mask`. Users can create, edit, and delete local files, import remote files that are periodically synchronized, and assemble combined files that reference multiple local and remote sources.

The application runs in the background with a menu‑bar icon, giving quick access to the editor and a one‑click way to activate a chosen hosts file. The editor layout includes a toolbar, a list of defined files, and a text pane for editing. Preferences allow showing the active file name in the status bar and configuring update intervals for remote sources.

Designed for macOS 13 (Ventura) or newer, Gas Mask is distributed as a free, open‑source binary that requires administrator privileges on first launch to modify `/etc/hosts`. It can be built from source with Xcode 15 or later.