Get it
Download FireLeash
One installer, no account, no service — free and open source. Bring your own Firefox: FireLeash drives it, it doesn't bundle it.
Heads up: the installer isn't code-signed yet, so Windows SmartScreen may warn on first run — click More info → Run anyway. The source is open if you'd rather build it yourself.
What it is
Any number of Firefox windows. One hood.
FireLeash tiles real Firefox windows into a single frame and switches between saved layouts instantly. Not a webview wearing a browser costume — the actual Firefox, with your profile, your extensions, your engine.
Real Firefox panes
Every pane is a genuine top-level Firefox window, reparented into the frame. Your profile, your add-ons, your rendering — nothing emulated.
Shared login, once
Import your Firefox profile a single time. Every pane runs as a window of one shared process, so you're signed in everywhere from the first launch.
One omnibox
FireLeash owns the address bar — back, forward, reload, navigate — and drives the exact pane you're in. Firefox's own chrome hides until you press ☰.
Workspaces
Named layouts of panes in resizable rows — reorder, swap, collapse. Switching hides windows instead of destroying them, so nothing reloads.
Lazy & light
A blank pane costs nothing; Firefox launches only when the pane first navigates. New tabs wear the mark until you fill them.
Free & open
No account, no telemetry, no price. MIT-licensed, source on GitHub, from the Divisionless workshop.
The real thing
Actual Firefox, actually tiled.
FireLeash — real Firefox windows herded into one frame, one omnibox driving the focused pane.
Under the hood
How it works
The Electron shell renders no web content of its own. It launches real Firefox and gets out of the way.
Owned-window embedding
A real top-level Firefox window is reparented as an owned child of the FireLeash frame through Win32 — owned top-level, not WS_CHILD (which blanks the window). Resize the frame or drag a divider and the Firefox windows track it.
One shared Firefox
A single Firefox process runs on one FireLeash-managed profile; each pane is another window forwarded into it with -new-window. Import your real profile once and every pane is already signed in.
A per-window control channel
Each window reports its own native handle over a local 127.0.0.1 socket, so the FireLeash omnibox drives the precise focused pane. No automation flag is set, so sites never hand the panes a bot-blocked session.
Read the full field manual — the design story, the gotcha ledger, and the approaches that failed →
The record
Build log
Everything that shipped, how it works, and how it was verified — including the wrong turns. Newest first.
2026-07-20 · Public release
Shipped to the world
Renamed MultiView → FireLeash, scrubbed clean, installer on GitHub Releases, and this site.
2026-07-19 · Hardening
Pre-release hardening — 20 bugs found, 19 fixed
A deep pass over the shared-Firefox lifecycle: orphan-reap, config bookkeeping, and lazy-launch races all fixed and re-verified on the installed build.
2026-07-18 · The pivot
Real Firefox windows as panes
Dropped built-in Chromium entirely — owned-window embedding, shared login, and a unified omnibox driving the exact pane.
Dig deeper
Documentation & source
Field manual
The full design story — architecture, the gotcha ledger, and the approaches that didn't work.
Read ↗Build log
Every shipped change, dated and verified, newest first — the whole journey.
Read ↗Source on GitHub
The Electron shell, the Win32 embedding, and the Firefox control channel. MIT.
github.com/Divisionless/fireleash ↗Releases
Every versioned build, with notes and the downloadable installer.
All releases ↗