Open the laptop in front of you. If it is a Mac, you are on certified Unix. Hand it to the child next to you, watching cartoons on an iPad — also Darwin underneath, the same family. The phone in your pocket: same. Walk through any data centre serving European video, and a sizeable share of those streams come off appliances running FreeBSD. Pick up a games console at the till in any electronics shop, and odds are very good it boots a fork of FreeBSD before it ever shows you a menu.
Unix is not in a museum. Unix is in the room.
Before this Bow gets into what Unix actually is (next Monday) or where it came from (the Monday after), we should look at where it lives. Because the genealogy and the standards both make more sense once you notice that you have been holding Unix all morning.
The Everyday Unix: Apple
The single largest carrier of certified Unix today is Apple.
Every version of macOS from 10.5 Leopard (2007) through macOS 15 Sequoia (2024) has been certified by The Open Group as conforming to the Single UNIX Specification, version 3 — branded UNIX 03. The certification is for the full macOS distribution, not for Darwin in isolation; Darwin (Apple's open-source layer — XNU kernel plus FreeBSD-derived userland) has never been certified on its own. But macOS as Apple ships it carries the trademark.
That is hundreds of millions of certified-Unix machines on desks, in bags, in living rooms, every day.
iOS, iPadOS, tvOS and watchOS share the Darwin foundation but are not separately certified. Still, the family resemblance is there: the same kernel inheritance, the same userland conventions, the same Unix-shaped system calls underneath the touch keyboards and the lock screens.
One footnote worth keeping. Apple is certified on UNIX 03, dating from 2002. Only one product on the planet is certified at the next level — UNIX V7 (Single UNIX Specification version 4, POSIX.1-2008): IBM's AIX 7. Apple, for reasons of its own, has not stepped up.
The Infrastructure Unix: Netflix
When you stream an evening's viewing on Netflix, the bits you receive almost certainly come off a server running FreeBSD.
Netflix's Open Connect Appliances — the boxes ISPs host in their own racks to bring Netflix's catalogue close to the viewer — run a lightly customised build of FreeBSD's development branch. Netflix publishes its work back upstream. The TLS offloading that lets a single appliance push around 375 gigabits per second on roughly half its CPU is a FreeBSD-13 feature, written by Netflix engineer Drew Gallatin in collaboration with Chelsio.
The Open Connect network pushes over 100 terabits per second at peak across thousands of these appliances. Estimates of Netflix's share of total internet traffic in peak hours land in the region of one third; the figure is a plausibility estimate, not an audited statistic, and worth a hedge. But the order of magnitude is not in dispute. A substantial share of evening internet, globally, is FreeBSD.
The point is not Netflix's brand. The point is that the largest single carrier of bits on the internet, at peak, runs on an operating system whose family tree goes back to 4.4BSD-Lite, which goes back to Berkeley, which goes back to Bell Labs.
The Console Unix: Sony
Both PlayStation 4 and PlayStation 5 boot a Sony-customised FreeBSD.
The PS4's Orbis OS is derived from FreeBSD 9
(2013 vintage). The PS5's Orbis 2.0 is derived from
FreeBSD 11.0
(__FreeBSD_version 1100122, for the
curious). Sony publishes the modified FreeBSD kernel
source on its open-source page, as the BSD licence
permits and good citizenship encourages.
Over 200 million PlayStation units have shipped since the PS3 (which already carried BSD lineage in a different form). Each one is, underneath the menus and the game launcher, a Unix-family machine.
The Router Unix: Juniper
Junos OS, which runs on a substantial part of the internet's backbone routing equipment, has been FreeBSD-based since its first release in July 1998. The classical Junos line tracks the FreeBSD versions: Junos R15.1 runs on FreeBSD 10, R21.1 on FreeBSD 12, R24.2 on FreeBSD 14.
Worth being precise here, since precision is part of what this Bow is about. Juniper has introduced Junos OS Evolved (from R18.3, 2018), a newer variant built on a Linux kernel rather than FreeBSD. Both lines exist in parallel. Classical Junos is still FreeBSD; Junos OS Evolved is not. When someone says "Juniper runs BSD", they are talking about the classical line.
Either way, when a packet crosses the internet between Frankfurt and Madrid, there is a non-trivial chance it passes through a router whose control plane is a direct descendant of Berkeley's 4.4BSD-Lite.
The Enterprise Unix: AIX, Solaris, HP-UX, z/OS
The world's commercial Unix systems are not all in retirement homes.
IBM AIX is actively developed. New versions track new IBM POWER processors; the public roadmap is clear. AIX 7 is the only operating system in the world certified at UNIX V7 (SUSv4) level. Banks, insurance, large enterprise back-office: AIX still carries this work, and IBM still treats it as core strategy.
Oracle Solaris is in what Oracle calls sustaining support. Security patches, critical bug fixes, no major new features. Solaris has not been the centre of Oracle's attention since the Sun acquisition in 2010, but it has not been killed. It still runs in telecom carrier infrastructure, in long-cycle replicated databases, in places that would be expensive to migrate and have no business reason to migrate.
HP-UX is the one that is genuinely fading. Its fortunes were tied to Intel's Itanium processor, which Intel discontinued. Hewlett Packard Enterprise still offers extended support contracts, but the platform has no forward path. It runs where it runs, and where it runs, it tends to stay until the hardware fails.
z/OS on IBM mainframes is certified Unix in a category most engineers never think about. It powers a substantial part of the world's banking transaction processing — the kind of system whose downtime appears in newspaper headlines because so few people remember it is there.
A Historical Footnote: WhatsApp on FreeBSD
For a long stretch — through the years when WhatsApp scaled to a billion users with a famously small engineering team — the backend ran on FreeBSD, with Erlang on top. After the Meta acquisition the stack changed. The point that survives the change is the one Rick Reed and Jan Koum made publicly at the time: FreeBSD's coherence and its network stack let a small team carry a very large user base. That, too, is part of where Unix has lived.
A Note on Linux
Some readers will be tilting an eyebrow by now and asking the reasonable question: what about Linux?
Linux is not in this list. Not because Linux is unimportant — it carries an enormous share of the world's cloud servers, embedded devices and Android phones — but because Linux is not Unix. It is Unix-like. Linus Torvalds wrote the Linux kernel from scratch in 1991, with no inherited Unix or BSD code. The standard userland comes from GNU, not from AT&T or Berkeley. Linux has never been certified by The Open Group and is not on the UNIX trademark register.
It is a separate family. It looks Unix-shaped because that was the design intent, but the genealogy is its own.
Next Monday's piece — the standards question — will be the place to talk properly about that line. Today's piece is about where the certified family and its direct BSD relatives are running right now. Linux's story is parallel, and we will give it its own room.
The Point
Unix is not a historical curiosity. It is the operating-system family under your phone, under your laptop, behind your Friday-evening stream, inside the router that carries your call, in the back office of the bank that holds your salary, and inside the console your nephew is shouting at in the next room.
You have been holding Unix all morning. The question for the rest of this Bow is what makes it Unix — and how this strange, fifty-seven-year-old family came to be everywhere at once without ever quite advertising itself.