Sashfold

A web browser engine written from scratch. Every byte.

HTML, CSS, layout, fonts, networking, image codecs — one repository, three operating systems.

Every byte of code that ships in a Sashfold binary is written in this repository.

No vendored libraries, no dependencies, no “temporary” borrowed code. The boundary is the operating system itself and the language runtime — the things every program on the machine already stands on. On Linux that goes all the way down: no GTK, no Qt, no SDL, not even libwayland — Wayland is a protocol over a socket, and Sashfold speaks it directly, the same way it speaks HTTP. The pledge is enforced by a CI gate that reads the built binary’s import table and fails the build if anything else appears.

What Sashfold will never do

No telemetry
No sponsored tiles
No default-search auction
No account requirement
No cloud AI
No feature-removal churn
No self-updater
No settings outside human-readable files

Zero dependencies is also a security stance: no supply chain to poison, no vendored CVE lag, nothing to audit but the one repository. Every parser is fuzzed from the week it is born.

Graded in public

Compatibility is never vibes here — it is numbers against fixed public yardsticks, enforced by baselines in CI that only ratchet upward.

7032 / 7032html5lib tokenizer tests — 100%

1784 / 1784html5lib tree construction — 100%

893 / 893WPT URL parsing — 100%

6759 / 13477WPT CSS reference tests — 50.2%, by directory

100 pagesthe Sashfold 100 — the live web, rendered nightly, every picture published

3 OSesbyte-identical rendering, proven in CI

The renderer is deterministic by construction — its own font, integer-only rasterization, no system text stack — so a page renders to the same bytes on Windows, Linux, and macOS. Reference screenshots are compared byte-for-byte on every commit, and so are screenshots of the browser chrome itself: a script drives the same shell the window uses, headlessly, on all three OSes. A live HTTPS page fetches, decompresses, parses, and renders to pixels in about a quarter of a second, through Sashfold’s own URL parser, HTTP/1.1 client, and inflate. Every night the engine renders a hundred pages of the live web — drawn from the Tranco list of the most visited domains — and the pictures go up unretouched, each with what its load cost: the Sashfold 100.

A page rendered by Sashfold: headings, wrapped paragraphs, bold, italic and linked text, a blockquote, bulleted and numbered lists, a bordered box, centered text and preformatted text — Rendered by Sashfold: parser → cascade → layout → paint, every stage in-repo.

The Sashfold Mono typeface sampler: uppercase, lowercase, digits, punctuation, and weight and slant variants at several sizes — Sashfold Mono — an original typeface authored as coordinate tables in the source, needing no font file at all. It is the last fallback: pages are set in the fonts already on the machine, read and rasterized by Sashfold’s own TrueType stack, and Sashfold Mono draws an honest box for anything none of them has.

Why another engine

Because the reading web deserves a fast, private, transparent way to read it — and because an engine whose every byte is in one place is an engine anyone can learn from, audit, or embed without dragging three hundred megabytes behind it. Sashfold competes with nobody but the spec.