FTL: A new operating system for clouds

What's FTL? You can build your own OS as a library. This userspace OS design makes it easy to add features, debug, upgrade the OS safely, as if writing applications. FTL kernel isolates containers (userspace OS instances) better than existing monolithic kernels, with a hypervisor-like interface based on a lightweight hardware-based isolation (user mode). You don't need bare-metal machines. FTL is compatible with Linux binaries. For example, the Rust-based HTTP server serving this website is a Linux application running on FTL. You can also run Unikernel-like specialized applications without POSIX abstractions. How it works Each container runs a userspace OS. It is a shared library which implements most of OS concepts such as Linux process, VFS, and TCP/IP. FTL kernel provides a minimal interface to implement Linux system calls in userspace, just like a hypervisor. FTL combines the best of microkernels (flexible & secure) and monolithic kernels (performant & simple). Our goal is to make lightweight containers as secure as VMs, and unlock new OS-level abilities in applications, without sacrificing performance: FTL Linux ┌────────────────────────────────┐ ┌────────────────────────────────┐ │┏━━━━━━━━━━━━━┓ ┏━━━━━━━━━━━━━┓│ │┏━━━━━━━━━━━━━┓ ┏━━━━━━━━━━━━━┓│ │┃ ┃ ┃ ┃│ │┃ ┃ ┃ ┃│ │┃ Linux ┃ ┃ Linux ┃│ │┃ Linux ┃ ┃ Linux ┃│ │┃ Process ┃ ┃ Process ┃│ │┃ Process ┃ ┃ Process ┃│ │┃ ┃ ┃ ┃│ │┃ ┃ ┃ ┃│ │┃╌╌╌╌╌ Linux system calls ╌╌╌╌╌┃│ │┗━━━━━━━━━━━━━┛ ┗━━━━━━━━━━━━━┛│ │┃ ┃│ └────────────────────────────────┘ │┃ Userspace OS ┃│ ╌╌╌╌╌╌╌╌ Linux's interface ╌╌╌╌╌╌╌ │┃ (Process, VFS, TCP, ...) ┃│ ╔════════════════════════════════╗ │┗━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┛│ ║ ║ └────────────────────────────────┘ ║ Linux Kernel ║ ╌╌╌╌╌╌╌ minimal interface ╌╌╌╌╌╌╌╌ ║ ║ ╔════════════════════════════════╗ ║ process, fork/exec, memory, ║ ║ FTL Kernel ║ ║ signals, TCP/IP, /proc, ║ ║ vCPU, memory, drivers, ... ║ ║ /dev, drivers ... ║ ╚════════════════════════════════╝ ╚════════════════════════════════╝ Userspace OS design also enables you to extend most of Linux kernel features without kernel/eBPF programming. You can add printfs, apply security updates, and add new features quickly and safely. In FTL, OS is just a library. Read more. Roadmap September 2026: Run a simple Linux HTTP server on FTL (released in v0.0.1 ✅) October 2026: Async Rust apps support - Linux threads, epoll, ... (released in v0.1.0 ✅) November 2026: Filesystem December 2026: Node.js / Go support January 2027: SMP, container images, 64-bit Arm support Links GitHub repository Introducing FTL: A new operating system for clouds (blog post)