The Project

What it is

macXserver is a modern X11 server for macOS written in Swift. I built the first usable version in 30 days as a personal challenge with Claude Code as an agentic AI coding partner. What it focuses on:

• Display scaling that doesn’t change your desktop resolution. Pick a comfortable size for X windows independent of the rest of the desktop.
• Scalable Mac fonts through the core X protocol. Every X font request resolves to a Core Text font at integer pointSize. The classic .pcf bitmap catalog isn’t shipped. xterm sits on the Mac desktop looking as good as iTerm2; xfontsel-style enumeration of bitmap families gets a curated list instead of a directory tree.
• X windows are first-class macOS windows. Real NSWindow per top-level. Optional Motif-style frame when you want it.
• Session capture and replay built in. Every wire interaction with the server can be recorded to a .xtap file and replayed against another server. Useful for debugging; useful for documenting how a real X client behaves.

The source is on GitHub . The 30-Day Sprint is the day-by-day record of what landed. The Features cards on the home page break down each piece with screenshots, and the Deep dives section has the longer articles about architecture and design decisions.

Why

I have a collection of vintage Unix workstations documented at OldSilicon.com . When I want to do real work, I’m usually at my Mac, but a couple of times a week I want to display an xterm or quickplot from one of the Suns and have it sit comfortably next to my native apps. The retro experience is great when I’m sitting in front of the original CRT; it’s not great when I’m forcing my modern Mac to pretend to be a 1995 Sun.

Quickplot in particular is mine. I wrote it as a flight-test plotting tool in 1990–91 when I was a contract engineer at NASA. The first version was raw Xlib; the second used Motif as the widget foundation with Xlib for the graphing surfaces. NASA still ships it. I want to be able to run it on my Mac and have it look right.