--- title: Moxnox 1.0: NT-Like, POSIX-Compatible OS Running Atop Btrfs description: Moxnox is a hobby operating system whose syscalls and low-level interfaces are modeled on Windows NT, while still running POSIX software recompiled for it.... canonical: https://daily.dev/posts/moxnox-1-0-nt-like-posix-compatible-os-running-atop-btrfs-0qyhsx8ns twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Moxnox 1.0: NT-Like, POSIX-Compatible OS Running Atop Btrfs | daily.dev og:description: Moxnox is a hobby operating system whose syscalls and low-level interfaces are modeled on Windows NT, while still running POSIX software recompiled for it.... og:url: https://daily.dev/posts/moxnox-1-0-nt-like-posix-compatible-os-running-atop-btrfs-0qyhsx8ns og:image: https://api.daily.dev/og/posts/0QYHSx8Ns.png og:image:alt: Moxnox 1.0: NT-Like, POSIX-Compatible OS Running Atop Btrfs og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Moxnox 1.0: NT-Like, POSIX-Compatible OS Running Atop Btrfs **[Hacker News](https://daily.dev/sources/hn)** · 10 min read · 0 upvotes · 0 comments ## Summary Moxnox is a hobby operating system whose syscalls and low-level interfaces are modeled on Windows NT, while still running POSIX software recompiled for it. Version 1.0 is about 130,000 lines of C++ and runs on amd64 and aarch64. It uses btrfs as its filesystem and is mature enough to self-host, meaning it can build itself. It implements 642 of roughly 1,200 POSIX 2024 functions, using musl, mingw, and tre for parts of its C library. Missing pieces include a GUI, multiple users, security, and working signal delivery mid-loop. The author says none of the substantive code was written by AI, though AI helped with mechanical porting tasks. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How many POSIX 2024 functions does Moxnox implement? Moxnox implements 642 of the roughly 1,200 functions defined in POSIX 2024, covering the vast majority of what gets used in practice. The gaps are patched over partly with gnulib. The project uses musl for math and cryptographic functions, mingw for printf and related functions, and tre for regular expressions. _Developers evaluating niche POSIX-compatible OS projects can track releases like this on daily.dev._ ### What is the Moxnox operating system and how is it related to Windows NT? Moxnox is a hobby operating system whose syscalls, calling convention, and low-level interfaces are modeled after Windows NT, while remaining POSIX-compatible so recompiled Unix software can run on it. Unlike ReactOS, it does not recreate NT's daemons or internal kernel structure, only its syscall-level contract. Binaries use the PE format with .exe or .dll extensions, and C++ exceptions go through SEH. _Those curious about alternative OS architectures can follow hobby kernel projects like this on daily.dev._ ### What is missing from Moxnox 1.0? Moxnox 1.0 lacks a GUI, support for different timezones and keyboard layouts, locales and non-UTF-8 character sets, any security, and multiple users or groups. Performance gaps include a slow userspace heap allocator, TCP limited to a 64KB window without MSS negotiation, and a dentry cache that never gets pruned, keeping inodes open until deleted. _Anyone weighing whether an early-stage hobby OS fits their experiments can track its progress via daily.dev._ ## Community take How the wider developer community reacted, aggregated from 2 discussions and 24 comments across hackernews (as of 2026-10-28). **TL;DR:** Discussion centers on the technical and historical merits of the NT kernel design that Moxnox emulates, with genuine admiration mixed with critiques of NT's real-world flaws, while direct reactions to Moxnox itself are largely impressed but sparse. **Sentiment:** 40% positive · 45% mixed · 15% skeptical **The case for** - Some praise NT as a genuinely designed kernel rather than a reimplementation, making it an interesting basis for a hobby OS. - Several find it impressive that the author claims none of the substantive code was AI-written. - Choosing PE over ELF is seen by at least one commenter as a reasonable call given ELF's dynamic linking mess. - People appreciate that Moxnox isn't just another Unix clone, contrasting it favorably with projects like ReactOS. **The pushback** - Some point out NT carries long-standing design misfeatures, like the I/O Manager/Object Manager/driver stack mess with no caching above drivers. - Hard file locking inherited from NT-style design is called a terrible modern-day burden, as seen in Windows Update pain. - One commenter found several of Moxnox's design decisions among the weirdest they've seen, specifically reacting to POSIX functions being placed in ucrtbase. - A commenter questions the rationale for basing the OS on NT at all, asking whether it offers real benefits like speed, security, or hackability. **By community** - hackernews (mixed): Conversation mostly veers into a deep, mixed-sentiment debate about NT's historical design merits and flaws rather than focused reaction to Moxnox itself, with scattered praise for the project's technical approach and AI-free claim. **Hottest debate:** Whether NT's kernel architecture was a triumph of deliberate design or simply VMS repackaged with its own baggage of misfeatures. **Open questions** - What concrete advantages does basing an OS on NT-style syscalls actually provide over a Unix-like design? - Will Moxnox implement hard file locking, and if so, how will it avoid the pain points seen in Windows? **Highlights** > IMHO this is one of the OSes with the weirdest decisions I've seen on here. I do agree with using PE instead of ELF, as the dynamic linking situation of the latter (and Unix-likes in general) is, to put it bluntly, a horrid mess. The POSIX functions are split over ucrtbase, iphlpapi, and ws2_32, as on Windows, with anything that Windows doesn't implement put in mnposix. LOL. POSIX in ucrtbase! Those are words that I never expected to see together. I used AI to help with the mechanical parts of porting I feel like it won't be long before someone comes up with a crazy chimera of an OS that can run DOS, Windows, Linux, BSD, and macOS binaries. It doesn't look like AI is replacing software developers, but rather boosting them quite significantly; there seems to be a lot of activity and new projects I've seen recently from many who aren't even using AI themselves, but must be somehow being inspired by others to do more. > — [userbinator on hackernews · 3 comments](https://news.ycombinator.com/item?id=50269360) > Too bad for all the horrible misfeatures that got designed in and that we still have to live with, like the entire I/O Manager/Object Manager/filters/driver stack mess, with no caching anywhere above the drivers. > — [Tuna-Fish on hackernews](https://news.ycombinator.com/item?id=50268371) > So.. Why NT? Is it fast? Is it secure? Does it allow modern features? Is it hackable? Or why? > — [bmacho on hackernews](https://news.ycombinator.com/item?id=50270954) > > None of the substantive code was written by AI. That is impressive > — [phendrenad2 on hackernews](https://news.ycombinator.com/item?id=50268402) > Hard file locking makes Windows Update into agony. I can see the 70s motivation for it, but it is a terrible burden in modern times. Hopefully is is not implemented here. > — [chasil on hackernews](https://news.ycombinator.com/item?id=50271899) **Source threads** - [hackernews](https://news.ycombinator.com/item?id=50267569) · 78 points · 24 comments - [hackernews](https://news.ycombinator.com/item?id=50241847) · 5 points · 0 comments ## Similar posts on daily.dev - [The LearnixOS Book](https://daily.dev/posts/the-learnixos-book-ukezi1gu6) · Hacker News · 4 upvotes · 0 comments - [Rust-Written Redox OS Sees Improvements For Running On Real Hardware](https://daily.dev/posts/rust-written-redox-os-sees-improvements-for-running-on-real-hardware-kxl0txsw1) · Phoronix · 116 upvotes · 7 comments - [Not Every Open Source OS Needs to Be Based on Linux, and These Six Aren’t](https://daily.dev/posts/not-every-open-source-os-needs-to-be-based-on-linux-and-these-six-aren-t-jdafoeixg) · It's Foss · 0 upvotes · 0 comments - [This Month in Redox](https://daily.dev/posts/this-month-in-redox-txywbaawn) · Lobsters · 25 upvotes · 0 comments --- Tags: [#linux](https://daily.dev/tags/linux), [#c](https://daily.dev/tags/c), [#c++](https://daily.dev/tags/c++) [View this post on daily.dev](https://daily.dev/posts/moxnox-1-0-nt-like-posix-compatible-os-running-atop-btrfs-0qyhsx8ns) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Moxnox 1.0: NT-Like, POSIX-Compatible OS Running Atop Btrfs","url":"https://daily.dev/posts/moxnox-1-0-nt-like-posix-compatible-os-running-atop-btrfs-0qyhsx8ns","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/moxnox-1-0-nt-like-posix-compatible-os-running-atop-btrfs-0qyhsx8ns"},"datePublished":"2026-10-28T08:58:54.178Z","dateModified":"2026-10-28T13:29:50.401Z","description":"Moxnox is a hobby operating system whose syscalls and low-level interfaces are modeled on Windows NT, while still running POSIX software recompiled for it....","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/9d6cc992b2191c02c6fd3fdccc3bab73?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/9d6cc992b2191c02c6fd3fdccc3bab73?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Hacker News","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Hacker News","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/hn","url":"https://daily.dev/sources/hn"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/moxnox-1-0-nt-like-posix-compatible-os-running-atop-btrfs-0qyhsx8ns","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"linux,c,c++","timeRequired":"PT10M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Hacker News","item":"https://daily.dev/sources/hn"},{"@type":"ListItem","position":3,"name":"Moxnox 1.0: NT-Like, POSIX-Compatible OS Running Atop Btrfs"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/moxnox-1-0-nt-like-posix-compatible-os-running-atop-btrfs-0qyhsx8ns#faq","mainEntity":[{"@type":"Question","name":"How many POSIX 2024 functions does Moxnox implement?","acceptedAnswer":{"@type":"Answer","text":"Moxnox implements 642 of the roughly 1,200 functions defined in POSIX 2024, covering the vast majority of what gets used in practice. 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