SVGO

SVG Optimizer. Removes editor metadata, collapses groups, shortens paths, and minifies without visual changes.

Setup

# Install SVGO as a CLI tool and Node.js library.
npm install -D svgo

CLI Usage

# Optimize a single SVG file and overwrite it.
npx svgo input.svg -o output.svg

# Optimize all SVGs in a directory recursively.
npx svgo -r -f ./icons --output ./icons-optimized

# Show optimization stats without writing.
npx svgo input.svg --pretty --indent 2 -o -

Programmatic API

// src/svg/optimize.ts — Optimize SVG strings programmatically with custom config.
import { optimize, Config } from "svgo";

const config: Config = {
  multipass: true,
  plugins: [
    "preset-default",
    "removeDimensions",
    {
      name: "sortAttrs",
      params: { xmlnsOrder: "alphabetical" },
    },
  ],
};

export function optimizeSvg(svgString: string): string {
  const result = optimize(svgString, config);
  return result.data;
}

Custom Plugin Configuration

// svgo.config.js — Project-level SVGO config. Disable plugins that break
// specific SVGs (e.g., keep viewBox, don't merge paths in icons).
/** @type {import('svgo').Config} */
module.exports = {
  multipass: true,
  plugins: [
    {
      name: "preset-default",
      params: {
        overrides: {
          removeViewBox: false,        // keep viewBox for responsive scaling
          mergePaths: false,           // don't merge — breaks some icon animations
          convertShapeToPath: false,   // keep semantic shapes (rect, circle)
        },
      },
    },
    "removeXMLNS",          // remove xmlns for inline SVG use
    "removeDimensions",     // remove width/height, rely on viewBox
    "sortAttrs",
    "removeStyleElement",
  ],
};

Batch Processing

// src/svg/batch.ts — Optimize all SVGs in a directory and report savings.
import { optimize } from "svgo";
import fs from "fs";
import path from "path";

export async function optimizeDirectory(inputDir: string, outputDir: string) {
  const files = fs.readdirSync(inputDir).filter((f) => f.endsWith(".svg"));
  let totalBefore = 0;
  let totalAfter = 0;

  fs.mkdirSync(outputDir, { recursive: true });

  for (const file of files) {
    const input = fs.readFileSync(path.join(inputDir, file), "utf-8");
    const result = optimize(input, { multipass: true, plugins: ["preset-default"] });

    totalBefore += input.length;
    totalAfter += result.data.length;

    fs.writeFileSync(path.join(outputDir, file), result.data);
  }

  const savings = ((1 - totalAfter / totalBefore) * 100).toFixed(1);
  console.log(`Optimized ${files.length} files. Saved ${savings}%`);
}

Writing a Custom Plugin

// src/svg/custom-plugin.ts — SVGO custom plugin that adds a class attribute
// to all <path> elements for CSS styling.
import type { CustomPlugin } from "svgo";

export const addPathClass: CustomPlugin = {
  name: "addPathClass",
  fn: () => ({
    element: {
      enter: (node) => {
        if (node.name === "path") {
          node.attributes.class = "icon-path";
        }
      },
    },
  }),
};

// Usage: optimize(svg, { plugins: [addPathClass] })

Build Integration

// vite.config.ts — Use vite-plugin-svgo to optimize SVGs at build time.
// SVGs imported as components are automatically optimized.
import { defineConfig } from "vite";
import svgo from "vite-plugin-svgo";

export default defineConfig({
  plugins: [
    svgo({
      multipass: true,
      plugins: [
        { name: "preset-default", params: { overrides: { removeViewBox: false } } },
        "removeDimensions",
      ],
    }),
  ],
});