SQLite in Browser using WebAssembly

In recent times, I have been hearing quite a lot about WebAssembly and I wanted to experiment with it. For those of you who do know what WebAssembly is, let me put is this way, it is a binary format which allows us to run native code written in C/C++/Rust inside a browser. This technology has a lot of potential.

For Instance, Autodesk, the company behind AutoCAD, has already started investing in it. You can now run AutoCAD in your browser! Yes you read it right. I repeat “YOU CAN NOW RUN AUTOCAD IN YOUR BROWSER!”

This is the current support for WebAssembly.

I wanted to experiment with WebAssembly myself and started to research (read google 😉) about it. I was looking to use some native library that I’m already familiar with. This is when, I came across sql.js. It is SQLite compiled to WebAssembly and can be used via JavaScript and I was able to run it successfully!

For the impatient ones, here is the demo and here is the source code. I want to emphasis that, this is just an experiment and I would not recommend to use this in production.

The setup

I’ll be showing, how to setup sql.js using webpack. I’ve used react for the UI in my demo, but you can use any framework of your choice. I’ll not go trough the UI code that I have in the the demo. I’ll be explaining just the setup process of sql.js.

I’m will be using webpack@4.40.2 and sql.js@1.0.0(the latest versions available at the time of writing this).

Let’s get started with the setup. First of all, you’ll need to install sql.js.

mkdir sqlite-wasm-demo
cd sqlite-wasm-demo
yarn add sql.js webpack

sql.js comes with two builds, a debug build and a production build. The debug build can be found at sql.js/dist/sql-wasm-debug.js and the production build can be found at sql.js/dist/sql-wasm.js. These files require sql.js/dist/sql-wasm-debug.wasm and sql.js/dist/sql-wasm.wasm respectively to be present, in order to work.

For ease of switching between the debug build and the production build, we can setup an alias for sql.js using webpack aliases.

// webpack.confis.js
const path = require('path');
const PROD = process.env.NODE_ENV === 'production';
const CopyWebpackPlugin = require('copy-webpack-plugin');

module.exports = {
	// rest of the config...
	resolve: {
		alias: {
			'sql.js': PROD
				? path.resolve(process.cwd(), './node_modules/sql.js/dist/sql-wasm.js')
				: path.resolve(process.cwd(), './node_modules/sql.js/dist/sql-wasm-debug.js'),
	// rest of the config...

You’ll also need to copy the corresponding .wasm file to the output folder. For this, I’ve use copy-webpack-plugin.

yarn add copy-webpack-plugin
// webpack.confis.js
const path = require('path');
const PROD = process.env.NODE_ENV === 'production';

module.exports = {
	// rest of the config...
	plugins: [
		new CopyWebpackPlugin([
				from: PROD
					? './node_modules/sql.js/dist/sql-wasm.wasm'
					: './node_modules/sql.js/dist/sql-wasm-debug.wasm',
				to: './',
	// rest of the config...

Now you can invoke, sql.js from your code.

// somewhere in your app
import initSqlJs from 'sql.js';

async function initApp(params) {
	const SQL = await initSqlJs();
	const db = new SQL.DATABASE();

	// no you can use sqlite!
	db.exec('SELECT 1;');


This should get you started with SQLite in the browser. The most common issue you might face, will most probably related to the path of .wasm files. It might depend on how you have configured your webpack. For most part, copying it to the same path as your entry .js file should work.

In the demo, I’ve include some data from fanzeyi/pokemon.json for you to play around. You can see the info about the tables by clicking on “Available tables” in the demo page.

I hope you find this exciting. If you have experimented with WebAssembly yourself and want to share your experience with me, you can tweet me @_vkbansal