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Apple's macOS dropped from official Unix registry

Apple's macOS dropped from official Unix registry

Rule Changes

macOS disappears from the last Unix register page that listed it

October 11th, 2026: Removal window narrowed to 7-11 October

Overview

Updated Oct 22

Apple's macOS has been removed from the Open Group's UNIX 03 certification list, the last register page where it still appeared in mid-October. That leaves IBM's AIX as the only system certified to the current UNIX 07 standard, according to OSnews.

Neither Apple nor the Open Group has said why. The register's other views still conflict, and Apple's unlinked company page carries 20 live macOS certificates with no expiry date.

Why it matters

The Open Group controls the Unix trademark. Without certification, Apple can't legally call macOS Unix — a label it has held since 2007.

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Key Indicators

19
Years of Unix certification
macOS was certified as Unix from Mac OS X 10.5 Leopard in 2007 until its removal from the register in October 2026.
20
Live macOS certifications on Apple's register page
An audit found Apple's company page, unlinked from the register's index, still lists 20 active Unix certifications covering macOS 26 Tahoe and macOS 15 Sequoia on both Apple silicon and Intel.
4
Register views that conflict on Apple
The Open Group's register publishes four different views of itself. Apple is absent from the full-register and by-company views, and until October had been present on the UNIX 03 product-standard view and its own company page.
38
Days macOS 27 went without a UNIX 03 entry
macOS 27 shipped on 14 September. By 22 October it had gone 38 days without a UNIX 03 entry on the Open Group's register.

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People Involved

TL
Terry Lambert
Engineer who led macOS Unix compliance effort
Historical figure in this story
 Fred Zlotnick
Fred Zlotnick
Former Sun Microsystems engineer, worked on macOS certification
Retired from Apple in 2023

Organizations Involved

Apple
Apple
Technology company
No longer listed on the Open Group's UNIX 03 certification page; Apple has not explained the removal

Apple is the maker of macOS, which has been certified as Unix since 2007.
The Open Group
The Open Group
Standards organization
Removed macOS from its UNIX 03 certification list; has not announced why

The Open Group is the standards organization that owns the Unix trademark and certifies operating systems as Unix-compliant.

Timeline

2007 October 2026

7 events Latest: October 11th, 2026 · 1 month ago
Tap a bar to jump to that date

  1. Removal window narrowed to 7-11 October

    Latest Registry Analysis

    Wayback captures show Apple entries present on the register's front page on 7 October and absent on 11 October, narrowing the removal window to four days.

  2. Open Group's Unix registry no longer lists macOS on some pages

    Registry Change

    macOS disappears from several views of the register of Unix-certified products. Hacker News users notice the removal.

  3. Audit finds Apple's macOS certifications still live on other register pages

    Registry Analysis

    An independent audit of the Open Group's register found Apple's company page, unlinked from the register's index, still lists 20 active Unix certifications. It also found the register's four views disagree, 52 certificates hidden in HTML comments, and no certificate page carrying an expiry field.

  4. macOS removed from UNIX 03 certification page

    Registry Change

    The Open Group's UNIX 03 product-standard list no longer includes macOS, after weeks in which that page was the last register view still showing Apple's certification.

  5. macOS 27 ships without UNIX 03 registration

    Certification

    macOS 27 shipped on 14 September. By 11 October it had gone 27 days without a UNIX 03 entry on the Open Group's register.

  6. macOS 15 Sequoia certified Unix 03

    Certification

    Sequoia appeared on the Open Group's register with separate entries for Apple Silicon and x86-64 versions.

  7. Mac OS X 10.5 Leopard becomes first Apple OS certified Unix

    Certification

    Apple's first Unix-certified operating system, following a compliance effort led by Terry Lambert.

Scenarios

1

Apple renews Unix certification, macOS returns to registry

Likely Resolves by Q2 2027

Discussed by: Hacker News commenters, who note that vendors are typically dropped for failing to pay renewal fees

Apple has maintained Unix certification for nearly two decades. If the removal was due to a lapsed renewal fee, Apple can pay and have macOS restored to the register. This is the most common path for vendors who want to keep certification, and Apple's history suggests it values the status.

2

Apple lets Unix certification lapse permanently

Possible Resolves by End of 2027

Discussed by: LavX News analysis, which questions the value of certification given the extensive modifications required

The LavX article argues that macOS certification requires disabling security features and extensive reconfiguration, suggesting the certification is maintained by a few Unix enthusiasts within Apple rather than as a strategic decision. With those enthusiasts retired, Apple may not see value in renewing.

3

Removal is partial — some macOS versions remain certified

Uncertain Resolves by End of 2026

Discussed by: Hacker News commenter nsagent, who reports seeing macOS 26 still listed

One Hacker News commenter says they see macOS 26 listed under the Unix 03 standard, suggesting the removal may apply to a specific version rather than all of macOS. If so, Apple retains certification for at least one version and the registry change is narrower than it first appears.

4

Open Group clarifies macOS is still certified — absence was a register error

Uncertain Resolves by End of 2026

Discussed by: The reptile.haus audit, which found the register's views contradict each other

The audit found Apple's company page still lists 20 live certifications and that no certificate page records an expiry date. The 'recently certified products' page carries a generated date of October 9, 2026, and an empty list, suggesting the site is being rebuilt. If the absence from some indexes is a website or rebuild error, Apple's certification never lapsed.

Historical Context

3 moments from history that rhyme with this story — and how they unfolded.

1993

Novell buys UNIX from Bell Labs (1993)

Novell acquired UNIX from Bell Labs, ending AT&T's ownership of the operating system. This changed what 'Unix' meant — it became a trademark and standard rather than a specific codebase.

Then

The Unix trademark passed through several owners before coming under The Open Group's control.

Now

Unix certification became a legal and standards matter, not a question of code lineage.

Why this matters now

This is why certification matters — Unix is now a trademark controlled by a standards body, not a specific operating system.

Mid-2000s

Apple's Unix trademark dispute (mid-2000s)

Apple launched macOS without proper Unix certification, leading to a trademark dispute with The Open Group. Terry Lambert was put in charge of making macOS Unix-compliant.

Then

Mac OS X 10.5 Leopard became the first Apple OS certified as Unix in 2007.

Now

Apple has maintained Unix certification for nearly two decades, renewing with each major macOS release.

Why this matters now

The current removal reverses nearly two decades of maintained certification, and the original dispute shows the legal stakes involved.

Various years

Oracle Solaris and Inspur K-UX dropped from Unix registry

Both products were dropped from the Open Group's register when their vendors failed to pay renewal fees. The product pages remain accessible but no longer appear on the register.

Then

The products lost their Unix certification status.

Now

The register reflects only vendors who actively maintain their certification through fee payments.

Why this matters now

This is the precedent for what may have happened to macOS — a simple failure to pay renewal fees rather than a deliberate decision.

Sources

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The Open Group Hacker News Hacker News The Register Unix & Linux Stack Exchange LavX News reptile.haus remio.ai Authon Blog Clarity Today Byte by Mahmud OSnews Hacker News Hacker News The Open Group The Open Group Hacker News