Menu bar gauge
Show a ring, a percentage, or both. The color shifts toward amber and red as your usage grows.
Open source · macOS 14+ · Universal binary · System Monitoring
Know your data cap
before it knows you
Set your monthly allowance and DataCapGuard keeps a live gauge in your menu bar, projects your month-end total, and warns you before you reach the cap.
Free & MIT licensed · Apple Silicon & Intel · Latest release
Features
Built to watch one number.
DataCapGuard does one job, tracking usage against your monthly cap, and keeps everything on your Mac.
Projection and 30-day chart
See used, left, projected and daily average, plus a Swift Charts bar chart of the last 30 days. The projection turns red if it would exceed your cap.
Warnings at your thresholds
Get notified at 75, 90 and 100 percent by default, or pick your own. Each warning fires once per billing period.
Choose what gets counted
Count all physical interfaces, Wi-Fi only, or Ethernet only. VPN and virtual interfaces are excluded by default to avoid double counting.
Hotspot mode
Enter a network name such as your iPhone and only traffic on that network counts, so home usage never mixes in.
Reliable counting
Samples every 5 seconds and right after wake, treats counter resets as a new baseline, and keeps daily totals across reboots. A manual adjustment lets you match your provider's meter.
Screenshots
See it in action.
Install
Up and running in a minute.
DataCapGuard is open source and not notarized with a paid Apple Developer ID, so macOS needs one extra step the first time.
- Download DataCapGuard-macOS.zip and unzip it.
- Move DataCapGuard.app to your Applications folder.
- Clear the quarantine flag once, then right-click the app and choose Open:
xattr -cr /Applications/DataCapGuard.app
- When prompted, allow Notifications so DataCapGuard can warn you Location access is optional and only needed for Hotspot mode to read your Wi-Fi name (System Settings Privacy Security Location Services).
Download
Get DataCapGuard for macOS
Free, forever. Built for macOS 14 Sonoma or newer, Apple Silicon and Intel.
Not notarized: on first launch right-click DataCapGuard.app → Open.
- macOS 14 Sonoma+
- Universal (Apple Silicon + Intel)
- MIT licensed · open source
- No ads, no accounts, no telemetry
- Built with Claude Code · how and why
FAQ
Questions, answered.
Is DataCapGuard really free and open source?
Yes. It is released under the MIT license, with no accounts, subscriptions or in-app purchases. The source is on GitHub, and there is an optional Support button if you want to chip in.
What permissions does it need?
Notifications, so it can warn you at your thresholds if you decline, it still tracks usage and shows a banner. Location is optional and only affects Hotspot mode, because macOS may hide the Wi-Fi name without it. It never asks for Accessibility, Screen Recording or Microphone access.
Where is my data stored?
Only on your Mac. Daily usage totals are saved as a JSON file in Application Support, and the app reads per-interface byte counters, never the contents of your traffic. Nothing is sent to any server.
Why isn't the app notarized?
Notarization requires a paid Apple Developer account, which this free project does not have. Right-click the app and choose Open once to launch it, or build it from source with Xcode.
Was this written by AI?
Yes. DataCapGuard was generated by Claude Code from a written spec as a clean-room reimplementation, with no code or assets from any commercial app. The full source is on GitHub under MIT, so you can read every line before you run it. It has had less human review than a hand-written app, so bug reports are welcome.
Support ❤️
Built by one person, given away for free.
DataCapGuard is a free, open-source alternative to paid utilities. If it earns a spot on your Mac, a coffee keeps the updates coming.
☕ Support Or on Ko-fi