Troubleshooting bundling with Webpack

Webpack > 5 ESM

For any project using Webpack, you´ll need the following rule in your webpack.config.js above version 5:

        test: /\.(m?js)$/,
        resolve: {
          fullySpecified: false


General cases

If you wish to use Webpack for your app with the code provided in the step-by-step examples section, you'll need to:

npx create-react-app nymapp --template typescript
cd nymapp

You'll then need to install the needed dependencies, head to your app's App.tsx file and paste the code provided in the step-by-step section.

Contract client


Using webpack, the Contract client for querying or executing might need polyfills. As create-react-app doesn´t allow you access to the Webpack config without ejecting, you'll overwrite it as follow:

Install contract-clients dependencies
npm install @nymproject/contract-clients @cosmjs/cosmwasm-stargate @cosmjs/proto-signing 

Head to you app's App.tsx file and replace the code by the one provided in the step-by-step examples section.


Copy the following to your terminal and run:

npm install react-app-rewired
npm install --save-dev crypto-browserify stream-browserify assert stream-http https-browserify os-browserify url buffer process
cat <<EOF > config-overrides.js
const webpack = require('webpack');
const path = require('path')
module.exports = function override(config) {
  const fallback = config.resolve.fallback || {};
  Object.assign(fallback, {
    "crypto": require.resolve("crypto-browserify"),
    "stream": require.resolve("stream-browserify"),
    "assert": require.resolve("assert"),
    "http": require.resolve("stream-http"),
    "https": require.resolve("https-browserify"),
    "os": require.resolve("os-browserify"),
    "url": require.resolve("url")
  config.resolve.fallback = fallback;
  config.plugins = (config.plugins || []).concat([
    new webpack.ProvidePlugin({
      process: 'process/browser',
      Buffer: ['buffer', 'Buffer']
  config.module.rules = (config.module.rules || []).concat([
        test: /\.(m?js)$/,
        resolve: {
          fullySpecified: false
  return config; 

Edit the package.json file as follows:

  "scripts": {
    "start": "react-app-rewired start",
    "build": "react-app-rewired build",
    "test": "react-app-rewired test",
    "eject": "react-scripts eject"