Soie - a light web engine, written to last

Why we wrote Soie

SliTaz has always run on old machines. In ten years the web engines we relied on left those machines, one after the other. These are the facts, with their sources.

March 2016
Chrome stops on 32-bit Linux

Google ends Chrome for 32-bit Linux: no more updates, no more security fixes. chromium-dev announcement
April 2016
The last WebKitGTK SliTaz can build

WebKitGTK 2.4.11 comes out. It is still the WebKit in the SliTaz packages today: no release of its series has come since, and the newer ones do not build on our tool chain. webkitgtk.org
April 2017
Firefox 53 needs a Pentium 4

Firefox ends Linux support for processors older than the Pentium 4 and the AMD Opteron (SSE2): a Pentium III or an Athlon XP no longer starts it. Mozilla support
June 2024
WebKit needs GCC 11.2

WebKit raises its compiler requirement to GCC 11.2, to build with C++23. A small distribution has to change its whole tool chain just to follow one library. WebKit bug 275507
October 2025
Firefox 144, the last for 32-bit Linux

Mozilla ends 32-bit x86 Linux with Firefox 144. Firefox ESR 140 keeps getting security updates "until at least September 2026". Mozilla blog
October 2026
Soie 0.1.0

So we wrote our own engine, one a single person can read from end to end, built with the compilers SliTaz has, for the machines SliTaz runs on. It does not try to be Firefox: it tries to show the web as it is, with little.

There is a second reason. A browser that needs half a gigabyte to show a page takes that memory from everything else, and today everything else includes the AI models people want to run on their own machine. A light engine is not only for old PCs.

Soie and Firefox, side by side

The same pages, opened in xsoie 0.1.0 and Firefox 153 ESR, on the same machine, each in a fresh window, scripts on.

Memory at its peak

Soie33 MB

Firefox650 MB

Processor time

Soie0.6 s

Firefox4.7 s

Until the page is ready

Soie1.7 s

Firefox8.7 s

Averages over the six pages below.

Page	Memory	CPU	Ready
www.slitaz.org	17 / 605 MB	0.09 / 3.83 s	0.5 / 6.5 s
Wikipedia, Linux	48 / 663 MB	1.51 / 4.91 s	2.7 / 8.9 s
Hacker News	16 / 614 MB	0.11 / 4.06 s	1.6 / 8.9 s
LWN.net	16 / 608 MB	0.12 / 4.16 s	1.4 / 8.9 s
MDN, CSS	22 / 633 MB	0.25 / 4.69 s	1.7 / 8.9 s
GitHub, torvalds/linux	79 / 779 MB	1.27 / 6.79 s	2.2 / 10.4 s

In each cell, Soie / Firefox.

Measured with tools/browser-bench.sh from the Soie sources, October 2026, on an Intel i7-13700H under SliTaz x86_64: median of 3 runs, live sites. Memory is the PSS of the browser's processes at their peak (shared pages counted once), CPU the processor time they used, ready the time until the page stopped working.

The same page, two engines

Screenshots of the same 1024×768 view, taken the same minute. The fonts differ (Soie uses DejaVu, as SliTaz does), the layout is the page's.

www.slitaz.org

Wikipedia

Wikipedia content under CC BY-SA.

MDN Web Docs

MDN content under CC BY-SA. Some of MDN's top bar controls are still missing in Soie.

What is inside

One engine, a few extensions, small browsers: each piece does one thing, and every choice is written down in DECISIONS.md.

libsoie

The engine. HTML parsed the way the WHATWG says (it passes the html5lib tree tests), the CSS cascade (it passes css-parsing-tests), blocks, inline text, tables, flexbox, grid, SVG, painted with FreeType and HarfBuzz. Restyle and layout are incremental: a page that changes costs what changed.

Extensions

What a browser needs beyond the engine, each a small module: cookies, content blocking, WebP, JavaScript with QuickJS (DOM, fetch, workers), and audio and video with FFmpeg, Media Source Extensions included: YouTube plays.

Browsers

xsoie for X11 and wsoie for Wayland, for the lightest systems; SoieView, a GTK 3 widget, for Toile, the SliTaz desktop browser.

Solid

Two outside audits before this release, one for speed, one for security; the tests run under AddressSanitizer and on real sites; random changes to pages are checked against a fresh layout.

Simple

Plain C99, a plain Makefile, no toolkit in the engine, no code generator, no build system to learn: make and it builds, on old compilers too.

Yours

BSD licence. A C API to embed the engine (soie.h), an ABI for extensions (ext.h), and a headless renderer, soie-render, for tests and screenshots.

Get Soie 0.1.1

On SliTaz, the lightest way to browse the web:

spk-add xsoie

Soie comes in packages, so that a system installs only what it needs:

Package	What it holds
soie	the engine, with cookies, content blocking, WebP and JavaScript
xsoie	the X11 browser
wsoie	the Wayland browser (x86_64)
soie-gtk	SoieView, the GTK 3 widget Toile uses
soie-media	audio and video, with FFmpeg and ALSA
soie-dev	headers, static library, pkg-config files, soie-render

From the sources, on any GNU/Linux with a C99 compiler, GNU make, pkg-config, FreeType, HarfBuzz, libpng and libjpeg (the browsers also want Xlib or Wayland, GnuTLS and zlib; the extensions libwebp, FFmpeg and ALSA, and QuickJS 2026-06-04):

wget https://hg.slitaz.org/soie/archive/0.1.1.tar.gz
tar xzf 0.1.1.tar.gz && cd soie-0.1.1
make && make check
make install PREFIX=/usr

The README tells the rest; the history is in the Mercurial repository.

What Soie does not do yet

Soie is young, and we would rather say it here than let you find out:

Google search and YouTube may stop answering after a while: their bot checks do not trust a JavaScript engine that is not SpiderMonkey or V8.
No JavaScript inside iframes yet.
No HSTS: an https page may be redirected to http.
No :hover or :focus styles.
No tabs in xsoie and wsoie (Toile has them).
Some pages still lay out differently from Firefox: the comparisons above show where we stand.

Bugs and ideas are welcome on the SliTaz forum.

The web, light.