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Converting SVG set to Iconify JSON

This example shows how to convert directory full of SVG files to Iconify JSON format.

As a source, this example uses Material Design icons from Templarian/MaterialDesign-SVG repository that is also available as @mdi/svg NPM package.

Install dependencies:

npm install @iconify/tools @mdi/svg --save

Then create file convert-mdi.ts and put this content:

tsimport { promises as fs } from 'fs';
import { dirname } from 'path';

// Installation: npm install --save-dev @iconify/tools @mdi/svg
import {
} from '@iconify/tools';
import type { IconifyInfo } from '@iconify/types';

// File to save icon set to
const target = 'json/mdi.json';

// SVG files location
const sourcePackageJSON = require.resolve('@mdi/svg/package.json');
const sourceSVGDir = dirname(sourcePackageJSON) + '/svg';

// Metadata (specific to MDI example, remove this for your code)
const metadataSource: string | null = require.resolve('@mdi/svg/meta.json');

// Prefix to use for icon set
const prefix = 'mdi';

// Expected icon size. Used in validating icons, remove if you do not need to validate icons
const expectedSize = 24;

// Icon set information
const info: IconifyInfo = {
   name: 'Material Design Icons',
   author: {
       name: 'Austin Andrews',
       url: '',
   license: {
       title: 'Open Font License',
       url: '',
       spdx: 'OFL-1.1',
   height: 24,
   samples: ['account-check', 'bell-alert-outline', 'calendar-edit'],

// Import icons
(async function () {
   // Import icons
   const iconSet = await importDirectory(sourceSVGDir, {

   // Set info = info;

   // Validate, clean up, fix palette and optimise
   await iconSet.forEach((name, type) => {
       if (type !== 'icon') {

       // Get SVG instance for parsing
       const svg = iconSet.toSVG(name);
       if (!svg) {
           // Invalid icon

       // Check icon size
       const viewBox = svg.viewBox;
       if (viewBox.width !== expectedSize || viewBox.height !== expectedSize) {
               `Icon ${name} has invalid dimensions: ${viewBox.width} x ${viewBox.height}`

       // Clean up and optimise icons
       try {
           // Clean up icon code

           // Replace color with currentColor, add if missing
           parseColors(svg, {
               defaultColor: 'currentColor',
               callback: (attr, colorStr, color) => {
                   return !color || isEmptyColor(color) ? colorStr : 'currentColor';

           // Optimise
       } catch (err) {
           // Invalid icon
           console.error(`Error parsing ${name}:`, err);

       // Update icon from SVG instance
       iconSet.fromSVG(name, svg);
   console.log(`Imported ${iconSet.count()} icons`);

   // Add metadata from meta.json
   if (metadataSource) {
       interface MDIMetaDataItem {
           id: string;
           name: string;
           codepoint: string;
           aliases: string[];
           tags: string[];
           author: string;
           version: string;

       const metaContent = JSON.parse(
           await fs.readFile(metadataSource, 'utf8')
       ) as MDIMetaDataItem[];
       metaContent.forEach((entry) => {
           const { name, aliases, tags } = entry;
           const cleanName = cleanupIconKeyword(name);
           if (iconSet.entries[cleanName] === void 0) {
               console.error(`Missing icon: ${cleanName}`);

           // Add categories
           tags.forEach((category) => {
               iconSet.toggleCategory(cleanName, category, true);

           // Add aliases
           aliases.forEach((alias) => {
               const cleanAlias = cleanupIconKeyword(alias);
               if (iconSet.entries[cleanAlias] === void 0) {
                   iconSet.setAlias(cleanAlias, cleanName);

   // Export to IconifyJSON, convert to string
   const output = JSON.stringify(iconSet.export(), null, '\t');

   // Create directory for output if missing
   const dir = dirname(target);
   try {
       await fs.mkdir(dir, {
           recursive: true,
   } catch (err) {

   // Save to file
   await fs.writeFile(target, output, 'utf8');

   console.log(`Saved ${target} (${output.length} bytes)`);
})().catch((err) => {

Assuming that TypeScript is set to compile to lib, compile file to JavaScript and run it:

node lib/convert-mdi

If you are not using TypeScript, remove types from code. If should not be hard because there aren't many lines to remove.

Prepared project is available in Iconify Tools GitHub repository.

How does it work?

There are comments in the code above that explain what is going on.

The process is simple:

  1. importDirectory() imports all icons from directory "svg" of @mdi/svg package.
  2. iconSet.forEach() is used to iterate all icons to:
    • toSVG() is used to get SVG instance that can be manipulated by various functions.
    • cleanupSVG() is used to clean up code (MDI has clean code, so nothing to clean up there, but for other icon sets it is needed).
    • parseColors() is used to change default color to "currentColor".
    • runSVGO() is used to optimise icon code.
    • iconSet.fromSVG() is used to update icon data in icon set.
  3. Then script handles metadata: adds categories and aliases for all icons.
  4. iconSet.export() is used to export icon set to JSON file.

Released under the Apache 2.0 License.