MetaPost & TikZ in the browser
MetaPost 2.11, pdfTeX 1.40, LuaTeX 1.21 and dvisvgm 3.4 compiled to WebAssembly. Pick an example, edit it, and it is typeset again in this tab: MetaPost with TeX labels, whole LaTeX and plain TeX documents, graph drawing and Lua under LuaTeX, and OpenType fonts through fontspec. No server.
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What you are looking at. In MetaPost mode the interpreter (mplib, 1.2 MB of wasm) runs in a Web Worker. Text in btex … etex is extracted before the run, typeset in one batched pdfTeX job, converted with MetaPost's own dvitomp, cached by content hash and handed back through mplib's make_text callback; glyphs become SVG paths through MetaPost's own backend. In the TeX modes the whole document goes through pdfTeX in DVI mode and then dvisvgm, with PGF's special handlers, so shadings, patterns, clipping, opacity and pgfplots come out as native SVG. A document that uses graph drawing, \directlua or luacode goes to LuaTeX instead (fetched the first time it is needed), and with the OpenType box ticked LuaTeX also has luaotfload, fontspec, unicode-math and the Latin Modern OpenType family, each face fetched when a document first uses it.
Output is byte-identical to TeX Live 2025's own mpost, latex and dvisvgm on the golden corpora.