macXserver: a modern X11 server for macOS, built in 30 days

Can one person + Claude Code build a functional X server for the Mac in 30 days?

macXserver is a modern X11 server for macOS. I built it because I have a basement of vintage Sun workstations (OldSilicon.com) and I wanted to display their X clients on my Mac with display scaling, anti-aliased fonts, and X windows as first-class macOS windows. Session capture and replay is built in.

This site is the feature descriptor and the build log.

macXserver running classic X applications alongside native Mac apps — macXserver running xterm, quickplot, and oclock from a Sun Ultra 5 alongside native Mac apps on a Studio Display.

30 days

~205 hours

138 wire interactions

14 high-velocity days

12+ live X clients

Features

What macXserver does differently. Each card opens a page with more screenshots and the technical detail.

Display scaling without changing your desktop

Pick the size of X windows independent of the rest of the desktop. macXserver windows scale on their own.

Anti-aliased font rendering, no compromises

Core Text rendering throughout. Monaco for monospaced cells, real proportional fonts for Motif. Reported metrics equal rendered metrics by construction.

X windows are first-class macOS windows

One NSWindow per X top-level. Real Mission Control behavior. Optional Motif-style window frame when you want it.

Session capture and replay

Every byte of every session can be recorded to a .xtap file and replayed against another server. Built in, not an afterthought.

Remote app launcher

One click from the Mac status menu to an X client running on a vintage Sun. Passwords in Keychain, optional verbose progress, two-stage menu grouped by host.

Shaped windows: oclock, xeyes, and friends

The SHAPE extension done right. Round windows, oval windows, and the Motif frame plays along.

Built-in resource editor with themes

Edit the X RESOURCE_MANAGER from inside macXserver. Theme switching, line-numbered code editor, reload without restart.

Map X font names to Mac fonts

X clients ask for fonts by classic names like 'fixed' or 'helvetica'. macXserver maps each one to a real Mac font. The mapping is user-editable and lives in a single small file.

The 30-day ledger

One short entry per day. What landed, what clicked, what got chased and didn't pan out.

Read the full ledger →