A small part of Wombit can stay in the menu bar. It shows how much space is available, keeps a daily history for What Changed, and tells you when space runs low or something grows fast. It only reads, and nothing about your files leaves your Mac.
Turning it on or off
It's on from the start, so history begins the day you install the app. The first time you open the app, a step explains what it does, with its switch on. macOS then says a login item was added.
To turn it off, open Settings › Menu Bar and turn off Keep a daily history. You can also turn it off in System Settings › General › Login Items & Extensions. If macOS has it turned off, Settings says so, with Open System Settings….
The menu bar item
The item shows the available space as text, such as "182 GB". To show only a symbol, set Menu bar item shows to Symbol only in Settings › Menu Bar.
Click it to see the space meter and what changed since yesterday (the four largest changes of 100 MB or more), whether a waiting macOS update fits while one is waiting, and buttons that open the app or What Changed.
If the item doesn't appear, macOS may be hiding it, or the menu bar may be full. Settings tells you when that happens, with Open Menu Bar Settings….
What it measures
- Every hour: the disk's free space.
- Once a day, at low priority: the places the catalog knows by a fixed path, such as caches, simulators, Docker, package caches, AI models and backups. It measures a little at a time and stops if it runs long.
- Each full scan of the startup disk records the catalog's places and every folder of 500 MB or more, so What Changed can also show what grew since the last scan.
It's built to stay under 30 MB of memory, and it never scans the whole disk. Without Full Disk Access it skips what it can't read, and it never asks for access a second time.
History is kept on your Mac: hourly samples for 60 days and one a day after that, daily measurements for three years, and the latest 60 scans of each folder.
What Changed
In the app, What Changed shows the Last 7 Days, the Last 30 Days or Since Last Scan. It starts with the answer, such as "Used space grew by 15.89 GB", then shows each day and which places grew or shrank.
Alerts
In Settings › Menu Bar, under Alerts:
- When space is low: less than 20 GB or 10% of the disk is available, whichever is more.
- When something grows by 10 GB or more in a day, such as "Docker grew 26 GB since yesterday".
Each alert has Review, which opens What Changed, and Snooze, which keeps it quiet for a day. macOS asks for permission before the first one.
When an app leaves Applications
When you move an app to the Trash, the menu bar item checks what it left behind. If it's 1 MB or more, or something it left still tries to run, a notification offers Review, which opens the app at those files, or Not Now. Nothing moves until you confirm in the review. Turn it off with When an app leaves Applications.
Room for a macOS update
When macOS says an update is waiting, the menu bar item asks Apple's update server how big it is, once per update, the way System Settings does. It estimates the room needed at twice the download, since Apple doesn't publish a figure for most updates, and says it's an estimate. You're alerted only when there isn't room. Turn it off with When there isn't room for a macOS update.
Free and Pro
The menu bar item and its meter are free, and history is kept for everyone from the first day. What Changed, the alerts and the watch on apps you remove are part of PRO, so upgrading shows the history you already have. The alert that there isn't room for a macOS update always comes, with or without Pro. See Free for good, no trial.