Ironclad
No written verdict yet. Here is what commenters said.
5recommend
1warn against
Nov 8, 2025first mention
Oct 2, 2026latest mention
Why people recommend it
“What I like most about ironclad is that it is fully posix-compliant”
“Ironclad has a POSIX API, so yes, in principle it should be possible.”
Show 1 more
“The MAC's are good”
Caveats and dissent
“I don't see any interesting specifications in the repo, just basic stuff like this MD5 spec [0] that doesn't verify whether the MD5 implementation is correct.”
Often compared with
Threads where it came up
Also written as Ironclad OS. Data: ironclad.json. Quotes are verbatim; the verdict and theme labels are written by a model from these comments, and every clause links to its sources.
All comments 8
https://sel4.systems/ is relevant in this space!
There is also LionsOS https://lionsos.org/ (SeL4-based).
“What I like most about ironclad is that it is fully posix-compliant”
“(partially) formally verified says right on the page”
“Ironclad has a POSIX API, so yes, in principle it should be possible.”
“I don't see any interesting specifications in the repo, just basic stuff like this MD5 spec [0] that doesn't verify whether the MD5 implementation is correct.”
“The MAC's are good”
“For typical end users, kernel on its own is useless. So this an example of OS which uses Ironclad kernel:”