svgo-mbt

WebAssembly build of svgo.mbt, an SVG optimizer written in MoonBit: all 34 plugins in svgo's preset-default, in its order and with its semantics. One 200 KB wasm-gc file plus a 2 KB loader, no other dependencies.

npm i svgo-mbt          # the library
npx svgo-mbt in.svg -o out.svg   # the command line tool, no install

import { optimize, plugins } from "svgo-mbt";

const r = await optimize(svgText, {
  precision: 3,        // decimal places (default 3)
  multipass: true,     // repeat until stable (default true)
  pretty: false,       // indent output (default false)
  // plugins: ["removeComments", "convertPathData", ...]  // explicit list, in order
});
r.data;          // optimized SVG
r.originalSize;  // bytes in
r.size;          // bytes out
r.passes;        // pipeline passes
r.applied;       // plugins that changed something

await plugins(); // [{ name, description, enabled }]

Command line

The bin is the same optimizer compiled for node, so it needs no toolchain:

npx svgo-mbt in.svg -o out.svg
cat in.svg | npx svgo-mbt > out.svg   # stdin, or pass "-" as the input
npx svgo-mbt icons -r -o dist         # a directory, recursively
npx svgo-mbt in.svg --stats           # size statistics on stderr
npx svgo-mbt in.svg --json            # {data, originalSize, size, passes, applied}
npx svgo-mbt --list                   # available plugins

Exit codes: 0 on success, 1 for a usage error, 2 when a file could not be parsed, with the failing names on stderr.

In a browser the module is fetched relative to the loader; pass your own URL to init(url) before the first optimize call if you host it elsewhere.

Requires WebAssembly GC and JS String Builtins (V8 13.6): Node 24+, Chrome 130+, Firefox 134+, Safari 18.4+.

Same-process timings against svgo 4.1 (ms per call, both multipass): a Sketch icon 0.07 vs 0.30, a 50 KB Inkscape drawing 3.5 vs 14.5, the 68 KB Ghostscript Tiger 7.8 vs 38. Playground and details: https://perfectpan.github.io/svgo.mbt/.

MIT.

Plugin entries may also be objects, for example:

await optimize(svg, {
  plugins: [{ name: "cleanupIds", params: { preserve: ["logo"], minify: false } }],
});

Top-level params: { cleanupIds: { preserve: ["logo"] } } works with either the default preset or an explicit plugin list. An entry's params object takes precedence over the top-level object for that plugin. Missing parameters use plugin defaults. removeComments.preservePatterns supports literal substrings and ^-prefixed literal prefixes, not full regular expressions.