An opinionated application server for React Single Page Applications.


Next.js and others are great but they favor use cases of landing pages and
ecommerce websites, providing them with SSR, “on the edge” deployment etc.

These are all great features but we don’t always need such complexity if all we
want to implement is a simple React app and a few API routes along.

Therefore there’s ASAP which:

  • … is a simple application server built on top of tinyhttp, esbuild
    and React
  • … strives to enable fast iterative development
  • … and get out of your way in production


  • ASAP is opinionated

  • ASAP builds both client and server code with esbuild, you don’t need to mess
    with build configuration (also because you can’t)

  • In development mode ASAP automatically reloads server code on changes, you
    don’t need to restart the asap serve to iterate

  • ASAP provides a very thin client side application framework on top of React
    with type safe routing


Initialize a new project:

mkdir example && cd example && pnpm init

Add dependencies to the project:

pnpm add react react-dom @mechanize/asap

Let’s create a simple app of two pages.

First of all create app.js in the root of your repository:

import * as React from "react";
import * as ASAP from "@mechanize/asap";

export let routes = {
  index: ASAP.route("/", async () => ({ default: Index })),
  hello: ASAP.route("/hello/:name", async () => ({ default: Hello })),

function Index() {
  return (
        Go to{" "}
        <ASAP.Link route={routes.hello} params={{ name: "World" }}>
          hello page

function Hello({ name }) {
  return <div>Hello, {name}!</div>;

ASAP.boot({ routes });

Let’s add a few simple API methods, create api.js file also in the root of the repo:

import * as api from "@mechanize/asap/api";

export let routes = [
  api.route("GET", "/todo", (req, res) => {
    res.send([{ id: "1" }]);
  api.route("GET", "/todo/:id", (req, res) => {
    res.send({ id: });

Now we can serve the app:

pnpm asap serve

Now for production you’d want to the optimized bundle first:

pnpm asap build --env production

And finally serve the app in production environment:

pnpm asap serve --env production

Design Overview

  • ASAP runs a tinyhttp server to serve HTML page skeletons (an empty page
    with <script> tags to launch the client application) and API requests
  • in development ASAP compiles client code with esbuild
  • in development ASAP compiles server code with esbuild, this allows to hot
    reload server code (on changes the bundle will be rebuilt and the next request
    will be served using newly built code)
  • in production esbuild is not used and built bundles are used instead
  • on client there’s @mechanize/asap library which provides suspense-enabled
    typesafe routing


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