Developer tools · operating system
Ironclad OS
People like that it is an open source, formally verified Unix-like kernel written in Ada, and that many UNIX programs reportedly run on it. Critics say it is not yet proven for real-time production use and that its verification claims are unclear.
Summarized from 16 comments.
People like that it is an open source, formally verified Unix-like kernel written in Ada, and that many UNIX programs reportedly run on it. Critics say it is not yet proven for real-time production use and that its verification claims are unclear.
- recommend
- 12
- criticize
- 4
- months recommended
- 2 of 13
Why people love it
Open source formally verified kernel · 3
A formally verified OS is a great step towards better security.
Nov 2025 · commentGreat to see an open source kernel written in Ada.
Nov 2025 · commentI know only one OS working on that which is open source Ironclad OS
Oct 2026 · comment
What people warn about
Verification claims not substantiated · 3
They don’t prove anything important about the kernel clearly at all.
Nov 2025 · commentI don't see any interesting specifications in the repo
Nov 2025 · commentit seems to be little more than a mission statement
Nov 2025 · comment
What hackers pick instead
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- Oberon System 3Recommended as a tiny, fast, self-hosting system and simple language that runs on Raspberry Pi. Critics call the language dated and not well suited to systems programming.25recommend
- Genode OSRecommended as a free, long-running capability-based microkernel OS framework for building secure special-purpose systems. Caveat: not yet a daily driver for most.14recommend
- PebbleOSPeople recommend it as an open-source smartwatch OS released under Apache-2.0, with rapid iteration on watch faces and apps possible. Critics say the browser build is slow and unstable, and it still includes some proprietary blobs.8recommend
Every quote
The 13 most detailed of 16 comments. Each links to the original.
I know only one OS working on that which is open source Ironclad OS
Recommends · Oct 2026 · in “Several vulnerabilities have been discovered in the Linux kernel”
A formally verified OS is a great step towards better security.
Recommends · Nov 2025 · in “Ironclad – formally verified, real-time capable, Unix-like OS kernel”
Great to see an open source kernel written in Ada.
Recommends · Nov 2025 · in “There's No Rust on This Ironclad Kernel”
They don’t prove anything important about the kernel clearly at all.
Criticizes · Nov 2025 · in “Ironclad – formally verified, real-time capable, Unix-like OS kernel”
I don't see any interesting specifications in the repo
Criticizes · Nov 2025 · in “Ironclad – formally verified, real-time capable, Unix-like OS kernel”
it seems to be little more than a mission statement
Criticizes · Nov 2025 · in “Ironclad – formally verified, real-time capable, Unix-like OS kernel”
I'm skeptical that this is actually production usable for the hard real-time use cases
Mixed · Nov 2025 · in “Ironclad – formally verified, real-time capable, Unix-like OS kernel”
fully posix-compliant, meaning that you can run a lot of UNIX programs on it already
Recommends · Nov 2025 · in “Ironclad – formally verified, real-time capable, Unix-like OS kernel”
My main concern is speed and the lack of capability based security.
Mixed · Nov 2025 · in “Ironclad – formally verified, real-time capable, Unix-like OS kernel”
it makes me happy to see it getting a bit more love
Recommends · Nov 2025 · in “Ironclad – formally verified, real-time capable, Unix-like OS kernel”
is not wanting to boot on my QEMU
Mixed · Nov 2025 · in “Ironclad OS project popping out Unix-like kernel using Ada”
I am huge fan of works like this
Recommends · Nov 2025 · in “Ironclad – formally verified, real-time capable, Unix-like OS kernel”
Commercial support is not free, and the pricing for that is almost always something you have to ask for.
Criticizes · Nov 2025 · in “Ironclad – formally verified, real-time capable, Unix-like OS kernel”
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