Order Flow on macOS and Linux: Porting a Windows Footprint Platform in 158 Lines

Since the first release, the most common request in our inbox has not been an indicator. It has been an operating system. Traders on a MacBook, traders on Ubuntu, all asking the same thing: when can I run this without a Windows VM?

This morning the answer went live: native macOS and Linux builds, in beta. This post is the build log — with the numbers, because the numbers surprised us.

Why the engine cost nothing

This is the part worth stealing if you build desktop software. The platform was Windows-only for a year, but three early decisions meant it was never Windows-bound:

• TLS is rustls, everywhere. The Rithmic connection is a WebSocket speaking Protocol Buffers over rustls — no OpenSSL on Linux, no SChannel on Windows, no Security.framework glue on macOS. One TLS stack, compiled into the binary, identical on all three.
• Credentials go through the OS keychain abstraction. The same crate targets Windows Credential Manager, macOS Keychain and the Linux Secret Service. We wrote that code once, a year ago, for Windows — the macOS and Linux paths were already inside it, waiting.
• No shell calls, no hardcoded paths. Not a single C:\, not one spawned .exe. Every data path is resolved by the framework (AppData on Windows, ~/Library/Application Support on macOS, XDG on Linux).

The proof it worked: our CI had been compiling and testing the full backend on Linux for months — as a type check, not because we planned this. When we finally pointed the release pipeline at a Mac and an Ubuntu runner, all three builds went green on the first run.

Where the 158 lines went

The titlebar. On Windows we draw our own window chrome — minimize, maximize, close, top-right, like every Windows app. Put that on macOS and you have committed a small crime: Mac windows have native traffic lights, top-left. So on macOS the window keeps its native controls overlaid on our bar, our Windows buttons compile away entirely, and the toolbar shifts 78 pixels right to leave them room. Platform detection is resolved at build time — the dead branches do not even ship in the binary.

The honesty gate. The NinjaTrader and Quantower bridges are Windows-only forever — not a porting decision, a physical one: they read charts inside applications that only exist on Windows. On macOS and Linux those options are gone from the data-source selector instead of sitting there as buttons that could never work. What remains is what actually works: Rithmic direct and crypto mode.

The updater plumbing. A Mac asking for updates identifies as darwin-aarch64 or darwin-x86_64 depending on the chip — both now resolve to the same universal archive, because we ship one binary that contains both architectures. Which brings us to the weights.

What the builds weigh, and why

• Windows .msi — 8.9 MB
• macOS .dmg, universal — 19.4 MB
• Linux .deb — 10.8 MB
• Linux AppImage — 83.8 MB

Same application, four numbers. The Mac build doubles Windows because universal means two complete binaries in one file — Apple Silicon and Intel. The AppImage is nine times the .msi because of a decision Microsoft made for us: Windows ships a system webview (WebView2), so our installer does not carry a rendering engine. Linux has no such guarantee, so the AppImage carries all of WebKitGTK inside it. The .deb stays small by depending on the system package instead. Nothing in those 84 MB is our code being bigger — it is the platform tax, itemized.

What beta means here, precisely

The macOS build was validated on physical hardware before shipping — installed from the actual artifact, Gatekeeper bypass confirmed, license login, live data, native titlebar. The Linux build is different, and we would rather say it plainly: it has passed CI, and no human has run it on bare metal yet. That is exactly what the beta badge on the download page means — not "expect crashes", but "you might be first".

Two things we are watching. First, rendering: Windows draws through WebView2, macOS through WKWebView, Linux through WebKitGTK — three engines, and a footprint chart at market speed is exactly the workload where they diverge. The chart has an FPS and render-time counter built into its status bar, bottom right; if you run the Linux build, that number is the single most useful thing you can send us. Second, credentials: on Linux they live in the Secret Service, which means gnome-keyring or KWallet must be running. GNOME and KDE users will never notice. i3 and Hyprland users will — the login works, but nothing persists across a restart until a keyring daemon is up.

The part we did not pay for

The macOS build is not notarized. Notarization requires the Apple Developer Program — $99 every year — and this platform is built on a $0 marketing budget by one person. So the first launch hits Gatekeeper, and the fix is one trip to System Settings → Privacy & Security → Open Anyway. We documented it on the download page instead of pretending it will not happen — the same posture as our unsigned Windows installer and its SmartScreen note. When the platform pays for its own certificates, both go away. Until then, honesty is cheaper than a certificate, and it compounds better.

If you have been waiting on a Mac or a Linux box: the builds are live. You get the same footprint, the same delta, the same broker-side data as the Windows version — computed by the exact same 0-lines-changed engine.