The Ironclad Operating System Kernel

Ironclad is a formally verified, real-time capable, UNIX-like operating system kernel for general-purpose and embedded uses. It is written in SPARK and Ada, and is comprised of 100% free software.

Ironclad features a familiar POSIX-compatible interface, true simultaneous preemptive multitasking, Mandatory Access Control (MAC), and support for hard real-time scheduling.

Why Choose Ironclad?

Free as in freedom

Ironclad is fully open source and distributed under the GPLv3, ensuring it remains free. No firmware blobs are needed or shipped with the kernel. Every piece of the stack is open source.

Formal verification

SPARK's state of the art formal verification is employed for ensuring absence of errors and correctness of huge swathes of Ironclad, like cryptography, MAC, and user-facing facilities.

Portable

Ported to several platforms and boards, and designed to be easily portable to many more. Dependency on only the GNU toolchain allows for easy cross-compilation.

Distributions and ecosystem

POSIX compatibility makes software porting and development easy. The project features distributions ready for download and use for all the available architectures and boards, the most prominent FOSS one is Gloire.

Recent news

util-ironclad 0.1.0 released

2025-Mar-04

This release marks the first release of util-ironclad, the ironclad alternative for util-linux that distro maintainers can use for providing system management userland utilities like blkid, ps, dmesg, lspci, mount/umount, and the like.

Moving from Paypal to Stripe for donations

2025-Mar-02

Ironclad will be moving for its donations to Stripe from Paypal. This is done to make our processing easier and allowing people to do donations without a PayPal account, just using a credit card or bank transfer. We feel this is way more privacy respecting and will

Ironclad 0.6.0 released

2025-Feb-01

This release comes after a long gap of releases, and has had massive work done on almost every aspect of the kernel. Because of this, I find it hard to summarize the changes, but a gist of it is:

Further news can be read here.

Who pays for Ironclad?

Ironclad is fully community supported by the use of donations. Donations enable us to spend more time working on the project and help cover development expenses. We appreciate donations of any size.

We are also happy to consider making particular improvements or changes, or giving specific technical assistance, in return for a donation. If you would like to discuss this possibility, please send us an email to streaksu@mailbox.org.

If desired, the name of the donor can be added to this site's thank you section in the index, please send us an email for that.

Thanks for your support!