An OS where authority is explicit
and nothing is ambient.

sigilOS is a capability-secure operating system written entirely in the Sigil language — no C, no ambient authority, no trust by default. Every resource access is a held capability, enforced at the hardware seam by the MMU. Contracts are proven statically — safety is verified before the code runs, not trusted at runtime.

Why we're different Read the docs Changelog

FAST

GPU-first compositor, zero-copy IPC, SIMD tiers, near-native dynarec for retro workloads.

🪶

EFFICIENT

Pi 3 / 1 GB floor always works. One HAL, two backends. No fat runtime or libc.

🔒

SECURE

Capability boundary at the hardware seam — runtime caps + the MMU. No ambient authority.

🪨

STABLE

Fault-isolated processes, auto-restart, verified TCB. Byte-reproducible bootstrap seed.


From the blog

All posts →
Sigil-Docs · July 5, 2026

x86-Pass Is Not ARM-Pass — a Fleet Sweep & How Close We Are to 1.0

1.0 just got scoped to ARM only, which makes it faster to reach. Real QEMU caught a codegen bug that silently gives wrong answers on ARM while passing clean on x86. A signing root-of-trust mixup got caught twice before it shipped.

Sigil-Docs · July 4, 2026

Down to One — a Fleet Sweep & How Close We Are to 1.0

App-signing closed. The installer closed. The kernel security domain closed. The security gate narrowed to a single item in flight. All three V3D boards staged one step from a real GPU triangle. An honest read on how close 1.0 actually is.

Sigil-Docs · July 4, 2026

Nobody Self-Merged the Crypto

A distributed-review experiment stalled for a dozen cycles, and every affected agent held their PRs rather than self-merge crypto and OOB-class code without sign-off. Director stepped in as reviewer of last resort. Plus: the desktop-metal milestone survived a reboot, and gate #2 stopped being ambiguous.


Where sigilOS fits

One safe language and one image that carry embedded rigor, verified security, and a real desktop at once — a fit no incumbent fills. We're honest about where we lead on real hardware today and where we don't. See the industry packets → Press or investor? Grab the media kit →

★ Safety-Critical & High-Assurance

Medical, avionics, defense, industrial. Memory-safe by construction, capability-isolated, and provable before it runs — the properties certification exists to establish, built into the substrate. On metal today; pre-certification, and honest about it.

Embedded & Edge / IoT

Appliances, gateways, sensor nodes. A 1 GB Pi-3 floor, one image that scales, capability-isolated peripherals, and a self-healing bootloader that fetches the driver it needs. No fat runtime, no ambient trust.

Gaming & Enthusiast — shipping now

Forge packs, verifies, and runs retro systems with capability-sandboxed cores and a signed Relic format — on your desktop and on a Pi. The beachhead you can download and run today.

The Sigil Language

AI-native, effect-typed, contract-carrying, self-hosting. For programmers who want memory safety, provable contracts, and no ambient authority — in one language, with the metal underneath.


Latest release

🛡️ July 2 — we published our own security review, before anyone asked
Most companies talk about security only after something goes wrong. We commissioned an independent red-team / blue-team review of the entire stack — language, kernel, drivers, filesystem, build pipeline — while we're still pre-1.0, and published what it found: real strengths, honest gaps, and a public remediation plan. No exploit details; full plain-language brief on GitHub. Read the security posture brief →
Brief →
🆕 July 1 — Forge ships on all three desktops, and a game runs native
Forge v0.1 native downloads are live for macOS, Linux, and Windows — one Sigil source, compiled per platform by cc0, each with a published SHA-256 (get it). A real CHIP-8 core runs a ROM natively on the new mem_map keystone. And @grio's newest flagship kicked off: the agnostic self-healing bootloader — if the machine lacks a driver, boot fetches it, verified before load.
Forge →
sigilOS 0.6.0 — x86 desktop + SRDX remote display (tagged 2026-06-24)
First non-ARM Lumen boot: the full desktop on x86-64 bare-metal QEMU · SRDX remote display end-to-end (Ed25519 one-use invite, relay mesh, SRDX-NET-RT-PASS) · mouse + audio integrated · Lumen-working capstone.
SRDX →
🎉 Now on real metal → the sigilOS login renders on physical hardware
The headline of the 0.7.0 cycle: the x86 login screen renders on @grio's real x86-64 box (VER=12 — titlebar, user cards with avatars, password field, all correct), and the Pi 4B renders + talks serial on metal (the cached-MMIO + GPIO-ALT0 mux fix). And as of June 29 the last mile is done: the VL805 USB keyboard types on Pi 4B metal — characters on screen at the login, after ~100 build-iterations. The full saga is in the changelog and the build journal.
Features →
In progress → 0.7.0 — the web milestone
Native all-Sigil build harness (Python + keystone retired from the emit path) · the font subsystem (composite glyphs + full-Unicode cmap + bounded rasterizer — a 1.0 gate) · the Lumen dock + Doom Pile window pile (Apps past 200 modules) · the unified Pi image (one SD, board-detects Pi 3B→4B→5 and scales from the floor) · WASM-4 carts run cap-sandboxed as EL0 apps (Forge system #75) · real TLS 1.3, SigDB, CAS dedup all live · a capability-architected browser.
Browser →

Features

★ SRDX Remote Desktop

Not RDP. Not VNC. A capability-secured kernel transport lane. GPU-delta, pixel-perfect, network-bottlenecked. Mode-1 pixel stream + Mode-2 rollback netplay. SRDX-NET-RT-PASS proven. Syscalls 109–116.

★ Forge — 75 Systems

From Fairchild Channel F (1976) through WASM-4 fantasy carts — run cap-sandboxed as EL0 apps. Save-state ABI + thumbnails. Xbox One BT + hotplug. 3-state BIOS manager. Rewind + scanline. ROM library + Smart Folder navigation. On a Pi 3.

Relics — Sigil Forge

One file. One game. Capability-secured. Forge packs ROMs + BIOS + saves into a Relic — a self-contained, verified container. forgery_verify.sg gates every launch. .ness / .sfcs / .zips.

★ sigilOS Browser

Cap-native multi-process browser. Per-tab EL0 isolation. Live cap inspector. Structural private mode. SRDX tabs. Honest extension zone. 0.7.0 sprint.

★ SWiM — Sigil Window Morph

Run Lumen — or Lumen-like apps — on macOS, Windows, Linux & web. Portable, 3D-accelerated windowing; every window flips between a GUI face and a real CLI. All-Sigil core, one C ABI, bindings for every language. @grio flagship RFC — Forge cross-platform first, 1.0 stays the priority.


Explore the docs

The staff

Meet the fleet that builds sigilOS — a Director who conducts, a Raspberry-Pi hardware oracle with final say, a compiler that gates every build, and the domain agents for kernel, drivers, video, FS, apps, OS, and gaming. Plus the hierarchy and how we work.

★ Competitive advantage

sigilOS vs QNX · LynxOS · FreeRTOS/Zephyr · seL4 · Linux · Windows · macOS. A dimension-by-dimension difference model — and the niche no one else fills: cap-secure-by-construction + verified-TCB + hard-RT + AI-desktop + Pi3→workstation + open, all at once.

SRDX overview

SRDX is sigilOS Remote Desktop eXchange — the OS's own capability-secured, kernel-native remote-desktop protocol. It streams the Lumen desktop pixel-perfect over a dedicated kernel transport lane (not RDP, not VNC), auto-negotiating SRDX first and falling back to RDP/VNC for any other client. See Features → SRDX for the proof chain, the viewer, and the technical deep-dive.

Chromium parity matrix

8-section ✅/🔲/🚫 table of web platform features vs Chrome. Intentional omissions called out explicitly.

What is sigilOS?

The pitch — capability model, all-Sigil, Pi 3 floor, rolling milestones.

Architecture overview

Kernel HAL · VFS · WM · net stack · driver model — the whole map.

Smart Folders & tags

The ratified file model — no physical folders, tag-driven, cap-scoped queries.

What sigilOS does

Capability security · the Four Pillars · real TLS 1.3 · content-addressed dedup · SigDB · the font subsystem · Smart Folders · multi-arch scale-with-hardware.

Roadmap

0.5 desktop ✅ · 0.6 all-3-Pi metal desktop ✅ (first git tag) · 0.6.x interactive + SRDX clients ◀ now → 0.7 web → 1.0 arch-gate → 2.0 local-AI. Rolling milestone releases.

The Sigil language →

Why Sigil, language reference, capability model in-language, writing Sigil.

Changelog

Every shipped milestone — features, proofs, image artifacts.