Menu bar
Always recording.
Even when it's quit.
Close the window and Tidemark carries on in the menu bar. Its icon gets a mark when something needs you. A small helper keeps recording while the app is quit.
Tidemark for Mac
The high-water marks
of your Mac.
How hard your Mac works and what fills its disk, recorded every minute and kept for weeks, with the highs marked.
CPU
12%
Tidemark 64%
A spike lasts a second. A full disk creeps up for months. Tidemark remembers both.
Now
Everything your Mac
is doing. At a glance.
Eight measures, each with its last hour, its high for the day and the week's tidemark. One sentence says how the Mac is doing.
CPU7 %
GPU11 %
Memory14.1 GB
Disk I/O3.4 MB/s
Download1.4 MB/s
Upload282 KB/s
Energy8.8 W
Disk space165 GB free
Performance
Slow on Wednesday?
Find out why.
Every measure over an hour to 14 days. Point at any moment and see what every app was doing.
MonTueWedThuFri
Tidemark 96% · Wed 14:57
Wed 14:57
96% CPU
Move across the chart
CPU reached 96% Incident · snapshot kept
4 minutes: mostly Xcode (71%) and Safari (9%).
Photos hung Hang report
From the report macOS wrote.
Memory pressure went red Incident · snapshot kept
22.8 GB used, swap up 1.4 GB in ten minutes.
Disk Map
Every folder,
to scale.
Each folder is a block inside its parent, sized by the space it really takes, with this week's growth outlined. The whole disk scans in about half a minute, on every core.
- Click to zoom in
- Free space shown
- Cloud folders on disk and in the cloud
- Reveal in Finder
Trends
Know when the disk
will be full.
Disk space over seven days to a year, how fast it's growing, and the folders that grew. And when, in the week, your Mac works hardest.
Disk space, 12 months
+11 GB a monthFull around March 2027
CPU by weekday and hour
Busiest: weekdays, 14:00 to 16:00
Always recording.
Ask ⌘K
Ask why.
Chat about your Mac with the AI you already use. It sees names, sizes and figures, and Tidemark changes nothing.
- Claude Code
- Codex
- Copilot
- Antigravity
Why was my Mac slow on Wednesday afternoon?
Your Mac's story.
Kept on your Mac.
Nothing leaves.
The history is one file on your Mac. No account, no server, no tracking.
Light on its feet.
Written in Rust. It reads every few seconds and slows down when you're not looking.
Never averaged away.
Each minute keeps its average and its peak, so a short spike still shows.
Sleep isn't a dip.
Time asleep or not recording is shaded, never drawn as zero.
Help on every screen.
Press ? anywhere for that screen's help.
Free, and open.
Free software under the GPL. Read the code, change it, share it.
Questions.
How is it different from Activity Monitor?
Activity Monitor shows this moment. Tidemark records every minute for up to 14 days, and a daily disk total for a year, so you can go back to Wednesday afternoon and see what was happening. It also maps the disk and marks the week's highs.
Does it slow my Mac down?
It reads every 2 seconds while you're watching and every 5 when you're not, and redraws at most once a minute when its window is behind others. Disk scans run when the Mac is idle and on power, or when you ask.
Why does it want Full Disk Access?
To see inside Mail, Safari, Photos and other protected folders on the Disk Map. Without it those folders are skipped and counted, and a banner says so. Everything else works without it.
Where is my history kept?
In one SQLite file in your Library folder, on this Mac only. Choose 3, 7 or 14 days of detail in Settings; a daily total of disk space is kept for a year.
Does Ask send my data anywhere?
Only when you ask, and only to the AI tool you chose, signed in with your own account. It sees names, sizes and figures, not the contents of your files. Tidemark works fully without it.
Is it free? Does it run on Intel or Windows?
It's free and open source under the GNU GPL. For now it's for Apple silicon Macs with macOS 13 or later.
Know your Mac.
Install it once and it keeps watch from the menu bar.
Apple silicon (M1 or later), macOS 13 or later.
- Open the disk image and drag Tidemark onto Applications.
- Open it once. macOS says it can't check the app, because it isn't notarised by Apple. Click Done.
- In System Settings › Privacy & Security, click Open Anyway. It opens normally after that.
- For the whole Disk Map, turn Tidemark on under Privacy & Security › Full Disk Access, then press Reload.
- To keep recording while it's quit, turn on Keep recording when quit in Settings, and allow Tidemark under General › Login Items if macOS asks.