flatline

A menu bar monitor for Apple Silicon Macs that shows CPU, memory, and network, and nothing else.

Keep an eye on the trace. Hope it never goes flat.

flatline is an alternative to all-in-one monitors like eul that tracks only these three things. It doesn't support Intel Macs or older versions of macOS, so it can use what Apple Silicon offers: load per Performance and Efficiency core cluster, and memory pressure the way macOS calculates it. It uses about 0.1% CPU at idle.

Status: 1.0. Signed, notarized and self-updating. See the PRD and changelog.

Features

• CPU: total, user/system, per-cluster (P / E) and per-core load, load average
• Memory: used / app / wired / compressed / cached with Activity Monitor's definitions, memory pressure, swap
• Network: live down/up rates using 64-bit counters (no false spikes at 4 GiB), session totals, active interface
• Menu bar item that keeps the same width as the numbers change, with text, trace, or text+trace styles
• Popover with 60-second traces and a per-core grid
• Terminal-style monospaced look with a phosphor accent; native light and dark mode
• Launch at login, automatic updates via Sparkle
• No telemetry, no root helper, no kernel extensions, no SMC access

Requirements

• macOS 27 or later
• Apple Silicon (M1 or newer)

Install

Download the latest DMG from flatline.banast.as, open it and drag flatline to Applications. Or use Homebrew:

brew install --cask banastas/tap/flatline

Either way, it updates itself after that.

Building from source

Requires Xcode 27+ and XcodeGen.

brew install xcodegen
xcodegen generate
open Flatline.xcodeproj

Sampler unit tests run without Xcode:

swift test --package-path Packages/FlatlineKit

Debug builds are ad-hoc signed and run on any Mac. Release builds are signed with the maintainer's Developer ID.

Releasing

1. Add a ## 0.2.0 (date) section to CHANGELOG.md. It becomes the release notes.

2. Run:

   scripts/bump-version.sh 0.2.0   # sets the version, increments the build number
   scripts/release.sh              # test, archive, sign, notarize, staple, add to the update feed
   scripts/deploy-site.sh          # publish flatline.banast.as: page, appcast, DMGs
   scripts/update-cask.sh          # point the Homebrew cask at the new DMG and push the tap
   

3. Commit site/appcast.xml, project.yml and the changelog.

release.sh --skip-notarize makes a signed but un-notarized DMG for a quick check.

One-time setup on the release Mac:

• Notary credentials: xcrun notarytool store-credentials flatline --team-id F87BNUZAVJ
• Sparkle's update-signing key, in the login keychain under account flatline. Back it up somewhere safe; without it, existing installs can't verify new updates. Export it with build/SourcePackages/artifacts/sparkle/Sparkle/bin/generate_keys --account flatline -x <file> and restore it with -f <file>.
• Homebrew tap: banastas/homebrew-tap cloned next to this repo (../homebrew-tap).
• Cloudflare: npx wrangler login. releases/ (every shipped DMG) lives only on the release Mac and the live site.

License

MIT