Always show every file's extension on Mac

macOS hides file extensions out of the box, so a folder can be full of .txt, .rtf, .jpg, and .pages files that all look nameless. To make every suffix visible for good, open Finder → Settings → Advanced and turn on Show all filename extensions. That one switch is permanent, applies to every folder, and is the setting most Mac users flip within a day of getting comfortable.

The permanent switch

This is the setting to change once and leave alone:

1. Click the desktop or open any Finder window.
2. Press Command+Comma to open Finder → Settings (older Macs label it "Preferences").
3. Click the Advanced tab.
4. Turn on Show all filename extensions.

The change takes effect immediately and survives restarts, updates, and new files — it's a system-wide preference, not a per-window view option. It behaves the same on macOS 13 Ventura, 14 Sonoma, and 15 Sequoia.

The Terminal equivalent

If you're setting up a new Mac and want to script it, or you just prefer the command line, the same preference lives in one key. Always keep the undo handy:

# Turn on extensions everywhere, then relaunch Finder
defaults write NSGlobalDomain AppleShowAllExtensions -bool true
killall Finder

# Undo — hide known extensions again
defaults write NSGlobalDomain AppleShowAllExtensions -bool false
killall Finder

The killall Finder line simply relaunches Finder so the change appears at once; your windows reopen a second later. This writes exactly the same preference as the checkbox, so the two routes are interchangeable — use whichever you'll remember.

Why "all" doesn't always mean all

Turn the setting on and you may notice a stubborn file or two still showing no suffix. That's not a bug — macOS lets any single file override the global preference. Someone (or some app) ticked Hide extension in that file's Info panel, and a per-file choice wins over the system default. To fix it:

1. Select the file and press Command+I to open Get Info.
2. Expand the Name & Extension section.
3. Uncheck Hide extension.

The same checkbox works in reverse if you ever want to hide the suffix on one specific file — say, a nicely named document you'll share — without turning the global setting back off. Between the Advanced preference and this per-file switch, you control extensions at both levels.

The next housekeeping switch

Once extensions are visible, the natural companion is seeing the files macOS keeps out of sight entirely — caches, dotfiles, and system items. Our guide on showing hidden files on Mac covers the Cmd+Shift+. shortcut and when it's safe to use.