@rivus/svgo

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 188 KB wasm-gc file plus a 2 KB loader, no other dependencies; 3.6× faster than svgo at the median, with output within 1.3% of svgo's size on the benchmark corpus and 0 px render difference.

npm i @rivus/svgo       # the library
npx @rivus/svgo in.svg -o out.svg   # the command line tool, no install (installed: `svgo-mbt`)

import { optimize, plugins } from "@rivus/svgo";

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 }]

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.

Only the built-in plugins run. JavaScript functions cannot run inside the wasm module, so do project-specific rewrites on the SVG string before or after optimize; the MoonBit library accepts custom plugins through Config::custom.

Command line

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

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

Writing files prints one row per file on stderr, with a totals line for several; -q silences it:

$ npx @rivus/svgo icons/close.svg icons/logo.svg -o dist
  icons/close.svg     836 B →    276 B   −67%
  icons/logo.svg     1.1 KB →    528 B   −54%
  2 files            2.0 KB →    804 B   −59%  1.9 ms

Exit codes: 0 on success, 1 for a usage error, 2 when a file could not be read, parsed, optimized or written, 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: Node 24+, Bun 1.4+, Deno 2, Chrome 130+, Firefox 134+, Safari 18.4+. CI runs the fixture suite under Node, Bun and Deno; details in the repository README under "Runtime compatibility".

Same-process timings against svgo 4.1 (ms per call, both multipass): a Sketch icon 0.10 vs 0.29, the 50 KB Tux drawing 5.7 vs 12.8, the 68 KB Ghostscript Tiger 10.1 vs 41.1. Playground and details: https://perfectpan.github.io/svgo.mbt/.

MIT.