Award-winning technology backed by ground-breaking research
seL4 is both the world's most highly assured and the world's fastest operating system kernel. Its uniqueness lies in the formal mathematical proof that it behaves exactly as specified, enforcing strong security boundaries for applications running on top of it while maintaining the high performance that deployed systems need.
seL4 is grounded in research breakthroughs across multiple science disciplines. These breakthroughs have been recognised by international acclaimed awards, from the MIT Technology Review Award, to the ACM Hall of Fame Award, the ACM Software Systems Award, the DARPA Game changer award, and more.
Protecting critical systems around the globe
seL4 protects critical systems from software failures and cyber-attacks. It allows non-critical functionality to run securely alongside critical payloads by enforcing strong isolation and controlled communication.
seL4 is used in a wide range of critical sectors, from automotive, aerospace and IoT to data distribution, military and intelligence. It has been successfully retrofitted into complex critical systems and has demonstrably prevented cyber-attacks. Government organisations on several continents have funded further development of seL4 and its ecosystem.
Supported by commercial service providers
seL4 is the leading choice for building highly reliable software. Commercial support is available to help you build or migrate your product to run on seL4 and benefit from its unparalleled security.
A number of Trusted Service Providers have been endorsed by the seL4 Foundation for their expertise and experience in systems and/or formal verification at various levels: kernel, kernel platform ports, user-level Operating Systems components, and applications.
Backed by an Open Source Foundation
seL4 is open source, supported by the seL4 Foundation, an open, transparent and neutral organisation. The seL4 Foundation's goal is to ensure that seL4 continues to be the most highly-assured operating-system technology, readily deployable with a diverse and stable ecosystem of supporting services and products.
seL4 is free to use; its maintenance and development cost are funded by the seL4 Foundation memberships.
Contributions from a strong ecosystem
seL4 and its related technologies receive contributions from developers around the world.
The microkernel code itself evolves through a tightly controlled process, safeguarded by the Foundation's Technical bodies, to preserve its security, high assurance, and mathematical proofs.
Frameworks, tools and components that run on top of seL4 can use seL4's formally verified protection mechanisms and are therefore easier to assess for correctness. This means they can evolve more rapidly and accept community contributions at a higher pace, increasing the ease of adoption of seL4.
Annual gathering at the seL4 Summit
The seL4 Summit is the annual international conference on the seL4 microkernel and all seL4-related technology, tools, infrastructure, products, projects, and people.
It brings together the entire seL4 community to learn about the seL4 technology, its latest advances, uses, successes, challenges and plans. The event showcases exciting seL4 development, research, real world applications and experiences, offering an opportunity to connect with other seL4 developers, users, providers, customers, supporters, potential partners and enthusiasts.
Development Roadmap
With an active, public development roadmap, seL4 continues to solidify its position as the leading secure operating system and the industry standard for verified software. Evolution drives every level of the seL4 ecosystem:
seL4 itself is expanding its support for an increasing range of platforms, architectures, configurations and features.
The ecosystem is expanding with the development of frameworks, tools, components and language support to facilitate the production of seL4-based systems.
The formal proofs, which make seL4 unique, evolve alongside seL4. They are constantly maintained, improved, and kept in lock-step with the seL4 code.
Documentation and learning material
Eager to learn how to use and build on seL4 or its related frameworks and tools like Microkit, CAmkES, and Rust language support?
Explore the wide range of learning material for seL4, from hands-on tutorials and comprehensive documentation to research articles and university courses.
Latest News
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Proofcraft achieved a significant milestone in the seL4 verification roadmap that was years in the making: the MCS configuration of seL4, providing support for mixed-criticality systems, is now proved to be correct on RISC-V.
This configuration is the largest new seL4 feature, indispensable for mixed criticality real-time applications such as automotive use cases. It contains wide-ranging changes to the kernel's implementation and API. Its verification therefore required considerable effort and has been a priority in the seL4 roadmap for a long time.
Proofcraft has now completed the verification of functional correctness for seL4 with MCS. Functional correctness is the largest and most central proof in the seL4 verification stack. The proof targets the RISC-V architecture and will now be ported to the Arm 64-bit architecture, as part of DARPA's PROVERS program.
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1 Jun 2026
We are pleased to welcome a new member - Gapfruit - to the seL4 Foundation.
Gapfruit is a Swiss technology company building trustworthy foundations for the systems society depends on - from industrial controls to energy infrastructure. To achieve this, Gapfruit combines microkernel operating systems with capability-based security and hardware-rooted trust - an approach grounded in standards from the Trusted Computing Group. Together, these technologies enable resilient, verifiable device operations for the critical systems that underpin modern infrastructure. By joining the seL4 Foundation, we aim to advance high-assurance computing in critical infrastructure and collaborate with the global seL4 community to make trustworthy systems the standard - not the exception.
Learn more about Gapfruit's work in their contributions to previous seL4 summit panels and talks.
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The seL4 Foundation thanks Proofcraft, silver sponsor of the seL4 Summit 2026.
Founded by the seL4 verification leaders, Proofcraft offers commercial support and projects in formal verification in general, and involving seL4 specifically. By applying mathematical machine-checked software verification, Proofcraft increases critical software systems' reliability, safety and security, for a verified future.
See here if you are interested in sponsoring the seL4 Summit 2026.
