Where apps hide your files
Zen is built on Firefox, so its profile is a folder of files that you can open from about:support. Here is where it normally sits on a Mac, what is inside it, and how to back it up or add a userChrome.css.
On a Mac, Zen is a Firefox-based browser and keeps its profiles in a lower-case zen folder inside Application Support:
~/Library/Application Support/zen/profiles.ini
~/Library/Application Support/zen/Profiles/<random-id>.Default (release)The profile folder name starts with a random string, so yours will differ. Zen's docs call the default profile <profile-id>.Default (release), and Mac paths quoted in Zen's own bug reports match that layout. Older test builds named it Default (alpha) or Default (beta), a second copy can end in -1, and bug reports also show names such as <id>.Profile 1. The next section confirms the real path in ten seconds; use it before you copy or edit anything.
Zen's guides all use the same route. Open Zen, type about:support in the address bar and press Return. In the Application Basics section, find Profile Folder and click Show in Finder. Zen's guides word the button several ways (Open Profile Folder, Open Directory, Open Folder), which are other platforms' labels; on a Mac, Firefox's own strings read Profile Folder and Show in Finder, and Zen inherits them.
about:profiles lists every profile with its Root Directory (the profile itself) and Local Directory (its cache), each with a Show in Finder button. This is also where you create, rename and set a default profile.
For comparison, Firefox on the Mac used for this guide has ~/Library/Application Support/Firefox/ holding a profiles.ini and a Profiles folder, with one subfolder per profile (names such as abcd1234.default-release). Zen follows the same pattern under zen.
Zen's guide on managing profiles lists the files that carry your browsing life. Names and roles only:
| File or folder | What it holds |
|---|---|
places.sqlite | Bookmarks and history |
cookies.sqlite | Login sessions (cookies) |
logins.json, key4.db, cert9.db | Saved passwords and the key that protects them |
prefs.js | Settings you changed, including about:config values |
extensions.json, extension-settings.json, extensions/ | Installed add-ons |
search.json.mozlz4 | Search engine choices |
sessionstore.jsonlz4, sessionstore-backups/ | Open tabs and recent copies |
zen-sessions.jsonlz4, zen-sessions-backup/ | Zen's own record of windows and Spaces (newer versions) |
chrome/ | Your userChrome.css, if you made one |
Do not open or share logins.json, key4.db or cookies.sqlite. They are the files that decide who can log in as you.
Zen's live-editing guide says to create a folder named chrome inside the profile folder, and inside it a blank file named userChrome.css, then restart Zen. For the stylesheet to load you also have to switch on toolkit.legacyUserProfileCustomizations.stylesheets in about:config. Zen's guide says that the browser's developer tools are off by default for security, and that devtools.chrome.enabled and devtools.debugger.remote-enabled need to be true for the live editing method it describes.
The folder is named chrome in lowercase. It has nothing to do with Google Chrome; it is the Firefox name for the browser's own interface.
Zen's docs describe a session backup system from version 1.18 onwards. In order:
about:support, then quit Zen completely.zen-sessions.jsonlz4 in the profile folder to zen-sessions.jsonlz4.bak, so you can go back.zen-sessions-backup folder, duplicate the newest zen-sessions-<date>.jsonlz4 file and rename the duplicate to zen-sessions.jsonlz4.zen-sessions-backup) and open Zen.To undo, quit Zen and put the .bak file back under its original name. For profiles updated from 1.17.15 or older, Zen's guide uses the same method with sessionstore.jsonlz4 and the sessionstore-backups folder.
Quit Zen completely first. Firefox-based browsers keep reading and writing the profile while they run, and Zen's guide warns that copying with the browser open can corrupt it. Then copy the whole profile folder to an external drive or a folder in Documents.
On the new Mac, Zen's guide for moving a profile goes: install Zen, open about:profiles, create a new profile, open its folder from about:support, quit Zen, paste in the files from the table, then set that profile as the default in about:profiles. If Zen opens with an incompatibility error, the guide says to move compatibility.ini out of the new profile folder.
The profile's cache is not in the profile folder. Like Firefox, Zen keeps it in a matching folder under Caches, and Mac paths in Zen's bug reports show it as:
~/Library/Caches/zen/Profiles/<random-id>.Default (release)The Local Directory line in about:profiles shows yours. A cache holds copies of web pages and images that the browser rebuilds as you browse. Clear it from Zen's own settings with the browser open rather than deleting files by hand.
The sessions and history files grow slowly. If the profile folder is large, du -sh on it from Terminal shows the total, and du -sh * inside it shows which item is heavy. The only deletions to make are Zen's own: clear history or site data from its settings.
Application Support is part of ~/Library, which Finder hides and Spotlight leaves out of ordinary results. The profile folder's own name is random, and the file names inside are generic, so a search for "zen" does not find them.
Type userChrome into Everywhere to see every stylesheet of that name, in Zen and in any Firefox profile, or zen-sessions to find the session file and its dated backups. places.sqlite lists the bookmarks file of every Firefox-family profile on the Mac. Press ⌘↵ to reveal the one you want. It searches file names only, not tabs or history, and it reaches these folders without Full Disk Access because Application Support and Caches are not protected.
Under ~/Library/Application Support/zen/Profiles/, in a folder named like <random-id>.Default (release). To be certain, open about:support in Zen and click Show in Finder next to Profile Folder.
Create a folder named chrome inside your profile folder and put userChrome.css in it. Zen's guide also says to enable toolkit.legacyUserProfileCustomizations.stylesheets in about:config, then restart.
Quit Zen, then copy the whole profile folder. To move to a new Mac, create a profile in about:profiles, close Zen, and paste the key files into the new profile folder.
Zen is Firefox-based and uses the same profile system, with profiles.ini in its zen folder. The about:profiles page is the safest way to see and change profiles.
Everywhere keeps track of every file on your Mac — including the folders Spotlight hides and drives you have unplugged. Free for a day, then $19 once.
Version 2.20.3 · macOS 13+ · 4.7 MB · notarised