go-tex

Pure-Go TeX that runs the real LaTeX classes — in Go and in the browser.

go-tex is a pure-Go (CGO_ENABLED=0) TeX effort. Its engine is a faithful re-implementation of TeX — the category-code mouth and gullet, a scaled-point stomach, math, OpenType fonts, and PDF/SVG output — and on top of it, it loads and runs the genuine LaTeX classes: \documentclass{article}, {report} and {book} execute the real, embedded .cls files (LPPL, verbatim) — not an emulation — in native builds and in the browser via js/wasm, with no TeXLive and no server.

A real \documentclass{article} document typesets a numbered title, a \tableofcontents shaped by the loaded class’s own \l@… macros, numbered sections and subsections, \chapter (report/book, with its own contents entry), numbered figure and table captions, itemize/enumerate, and math.

Everything is pure Go (CGO_ENABLED=0), standard-library-first, go vet clean, and cross-compiles to every 64-bit Go target as well as js/wasm and wasip1/wasm. Licensed BSD-3-Clause.

The pipeline

The engine is built the way TeX parity is actually reachable — reimplement each stage faithfully, then gate it with an objective oracle.

Fidelity gates

Two oracles hold the line:

• a byte-exact conformance ratchet (TestConformance), TeX snippets checked byte-for-byte against real-TeX output; and

• a whole-document prose fidelity check against a real LaTeX engine (tectonic). On a corpus of 154 real arXiv papers with a reference PDF each, a vocabulary-bounded word census puts the median at 101% of the reference engine’s prose words (measured 2026-10-04); 10 of the 154 fall below 95% and 3 below 90%. Pagination lands on the reference exactly for 37 of them, with a total page deviation of 342 over the corpus.

  A median above 100% is expected rather than flattering: the engine emits each formula’s source as an invisible text layer so that maths can be found, copied and read aloud, and the census counts it. The figure to watch is the tail — the papers below 95% — not the median.

Scope — honest limits

The engine loads and runs the standard base classes; it is functional-parity-oriented and held to real-LaTeX fidelity, not a claim of full TeXLive parity.

Four classes are embedded as genuine .cls files and run as real TeX — article, report, book and amsart — so they need no filesystem and work in the js/wasm build too. Any other resolvable .cls or .sty is loaded and run as real TeX as well; what is not resolvable falls back to content-preserving emulation. The heavy packages are the honest gap: TikZ/pgf drawing is gated behind GOTEX_PGF and still in bring-up — see the roadmap.

Packages