Waku

Introduction

Waku (wah-ku) or わく means “framework” in Japanese. As the minimal React framework, it’s designed to accelerate the work of developers at startups and agencies building small to medium-sized React projects. These include marketing websites, light ecommerce, and web applications.

We recommend other frameworks for heavy ecommerce or enterprise applications. Waku is a lightweight alternative bringing a fun developer experience to the server components era. Yes, let’s make React development fun again!

Getting started

Start a new Waku project with the create command for your preferred package manager. It will scaffold a new project with our default Waku starter.

npm create waku@latest

Node.js version requirement: ^20.8.0 or ^18.17.0

Rendering

While there’s a bit of a learning curve to modern React rendering, it introduces powerful new patterns of full-stack composability that are only possible with the advent of server components.

So please don’t be intimidated by the 'use client' directive! Once you get the hang of it, you’ll appreciate how awesome it is to flexibly move server-client boundaries with a single line of code as your full-stack React codebase evolves over time. It’s way simpler than maintaining separate codebases for your backend and frontend.

And please don’t fret about client components! Even if you only lightly optimize towards server components, your client bundle size will be smaller than traditional React frameworks, which are always 100% client components.

Server components

Server components can be made async and can securely perform server-side logic and data fetching. Feel free to access the local file-system and import heavy dependencies since they aren’t included in the client bundle. They have no state, interactivity, or access to browser APIs since they run exclusively on the server.

// server component
import db from 'some-db';

import { Gallery } from '../components/gallery';

export const Store = async () => {
  const products = await db.query('SELECT * FROM products');

  return <Gallery products={products} />;
};

Client components

A 'use client' directive placed at the top of a file will create a server-client boundary when imported into a server component. All components imported below the boundary will be hydrated to run in the browser as well. They can use all traditional React features such as state, effects, and event handlers.

// client component
'use client';

import { useState } from 'react';

export const Counter = () => {
  const [count, setCount] = useState(0);

  return (
    <>
      <div>Count: {count}</div>
      <button onClick={() => setCount((c) => c + 1)}>Increment</button>
    </>
  );
};

Shared components

Simple React components that meet all of the rules of both server and client components can be imported into either server or client components without affecting the server-client boundary.

// shared component
export const Headline = ({ children }) => {
  return <h3>{children}</h3>;
};

Weaving patterns

Server components can import client components and doing so will create a server-client boundary. Client components cannot import server components, but they can accept server components as props such as children. For example, you may want to add global context providers this way.

// ./src/pages/_layout.tsx
import { Providers } from '../components/providers';

export default async function RootLayout({ children }) {
  return (
    <Providers>
      <main>{children}</main>
    </Providers>
  );
}

export const getConfig = async () => {
  return {
    render: 'static',
  };
};

// ./src/components/providers.tsx
'use client';

import { Provider } from 'jotai';

export const Providers = ({ children }) => {
  return <Provider>{children}</Provider>;
};

Server-side rendering

Waku provides static prerendering (SSG) and server-side rendering (SSR) options for both layouts and pages including all of their server and client components. Note that SSR is a distinct concept from RSC.

tl;dr:

Each layout and page in Waku is composed of a React component hierarchy.

It begins with a server component at the top of the tree. Then at points down the hierarchy, you’ll eventually import a component that needs client component APIs. Mark this file with a 'use client' directive at the top. When imported into a server component, it will create a server-client boundary. Below this point, all imported components are hydrated and will run in the browser as well.

Server components can be rendered below this boundary, but only via composition (e.g., children props). Together they form a new “React server” layer that runs before the traditional “React client” layer with which you’re already familiar.

Client components are still server-side rendered as SSR is separate from RSC. Please see the linked diagrams for a helpful visual.

Further reading

To learn more about the modern React architecture, we recommend Making Sense of React Server Components and The Two Reacts.

Routing

Waku provides a minimal file-based “pages router” experience built for the server components era.

Its underlying low-level API is also available for those that prefer programmatic routing. This documentation covers file-based routing since many React developers prefer it, but please feel free to try both and see which you like more!

Overview

The directory for file-based routing in Waku projects is ./src/pages.

Layouts and pages can be created by making a new file with two exports: a default function for the React component and a named getConfig function that returns a configuration object to specify the render method and other options.

Waku currently supports two rendering options:

• 'static' for static prerendering (SSG)

• 'dynamic' for server-side rendering (SSR)

For example, you can statically prerender a global header and footer in the root layout at build time, but dynamically render the rest of a home page at request time for personalized user experiences.

// ./src/pages/_layout.tsx
import '../styles.css';

import { Providers } from '../components/providers';
import { Header } from '../components/header';
import { Footer } from '../components/footer';

// Create root layout
export default async function RootLayout({ children }) {
  return (
    <Providers>
      <Header />
      <main>{children}</main>
      <Footer />
    </Providers>
  );
}

export const getConfig = async () => {
  return {
    render: 'static',
  };
};

// ./src/pages/index.tsx

// Create home page
export default async function HomePage() {
  const data = await getData();

  return (
    <>
      <h1>{data.title}</h1>
      <div>{data.content}</div>
    </>
  );
}

const getData = async () => {
  /* ... */
};

export const getConfig = async () => {
  return {
    render: 'dynamic',
  };
};

Pages

Pages render a single route, segment route, or catch-all route based on the file system path (conventions below). All page components automatically receive two props related to the rendered route: path (string) and query (string).

Single routes

Pages can be rendered as a single route (e.g., about.tsx or blog/index.tsx).

// ./src/pages/about.tsx

// Create about page
export default async function AboutPage() {
  return <>{/* ...*/}</>;
}

export const getConfig = async () => {
  return {
    render: 'static',
  };
};

// ./src/pages/blog/index.tsx

// Create blog index page
export default async function BlogIndexPage() {
  return <>{/* ...*/}</>;
}

export const getConfig = async () => {
  return {
    render: 'static',
  };
};

Segment routes

Segment routes (e.g., [slug].tsx or [slug]/index.tsx) are marked with brackets.

The rendered React component automatically receives a prop named by the segment (e.g., slug) with the value of the rendered segment (e.g., 'introducing-waku').

If statically prerendering a segment route at build time, a staticPaths array must also be provided.

// ./src/pages/blog/[slug].tsx

// Create blog article pages
export default async function BlogArticlePage({ slug }) {
  const data = await getData(slug);

  return <>{/* ...*/}</>;
}

const getData = async (slug) => {
  /* ... */
};

export const getConfig = async () => {
  return {
    render: 'static',
    staticPaths: ['introducing-waku', 'introducing-pages-router'],
  };
};

// ./src/pages/shop/[category].tsx

// Create product category pages
export default async function ProductCategoryPage({ category }) {
  const data = await getData(category);

  return <>{/* ...*/}</>;
}

const getData = async (category) => {
  /* ... */
};

export const getConfig = async () => {
  return {
    render: 'dynamic',
  };
};

Static paths (or other config values) can also be generated programmatically.

// ./src/pages/blog/[slug].tsx

// Create blog article pages
export default async function BlogArticlePage({ slug }) {
  const data = await getData(slug);

  return <>{/* ...*/}</>;
}

const getData = async (slug) => {
  /* ... */
};

export const getConfig = async () => {
  const staticPaths = await getStaticPaths();

  return {
    render: 'static',
    staticPaths,
  };
};

const getStaticPaths = async () => {
  /* ... */
};

Nested segment routes

Routes can contain multiple segments (e.g., /shop/[category]/[product]) by creating folders with brackets as well.

// ./src/pages/shop/[category]/[product].tsx

// Create product category pages
export default async function ProductDetailPage({ category, product }) {
  return <>{/* ...*/}</>;
}

export const getConfig = async () => {
  return {
    render: 'dynamic',
  };
};

For static prerendering of nested segment routes, the staticPaths array is instead composed of ordered arrays.

// ./src/pages/shop/[category]/[product].tsx

// Create product detail pages
export default async function ProductDetailPage({ category, product }) {
  return <>{/* ...*/}</>;
}

export const getConfig = async () => {
  return {
    render: 'static',
    staticPaths: [
      ['same-category', 'some-product'],
      ['same-category', 'another-product'],
    ],
  };
};

Catch-all routes

Catch-all or “wildcard” segment routes (e.g., /app/[...catchAll]) are marked with an ellipsis before the name and have indefinite segments.

Wildcard routes receive a prop with segment values as an ordered array. For example, the /app/profile/settings route would receive a catchAll prop with the value ['profile', 'settings']. These values can then be used to determine what to render in the component.

// ./src/pages/app/[...catchAll].tsx

// Create dashboard page
export default async function DashboardPage({ catchAll }) {
  return <>{/* ...*/}</>;
}

export const getConfig = async () => {
  return {
    render: 'dynamic',
  };
};

Layouts

Layouts are created with a special _layout.tsx file name and wrap the entire route and its descendents. They must accept a children prop of type ReactNode. While not required, you will typically want at least a root layout.

Root layout

The root layout placed at ./pages/_layout.tsx is especially useful. It can be used for setting global styles, global metadata, global providers, global data, and global components, such as a header and footer.

// ./src/pages/_layout.tsx
import '../styles.css';

import { Providers } from '../components/providers';
import { Header } from '../components/header';
import { Footer } from '../components/footer';

// Create root layout
export default async function RootLayout({ children }) {
  return (
    <Providers>
      <link rel="icon" type="image/png" href="/images/favicon.png" />
      <meta property="og:image" content="/images/opengraph.png" />
      <Header />
      <main>{children}</main>
      <Footer />
    </Providers>
  );
}

export const getConfig = async () => {
  return {
    render: 'static',
  };
};

// ./src/components/providers.tsx
'use client';

import { createStore, Provider } from 'jotai';

const store = createStore();

export const Providers = ({ children }) => {
  return <Provider store={store}>{children}</Provider>;
};

Other layouts

Layouts are also helpful in nested routes. For example, you can add a layout at ./pages/blog/_layout.tsx to add a sidebar to both the blog index and all blog article pages.

// ./src/pages/blog/_layout.tsx
import { Sidebar } from '../../components/sidebar';

// Create blog layout
export default async function BlogLayout({ children }) {
  return (
    <div className="flex">
      <div>{children}</div>
      <Sidebar />
    </div>
  );
}

export const getConfig = async () => {
  return {
    render: 'static',
  };
};

Root elements

The attributes of <html>, <head>, or <body> elements can be customized with the root element API. Create a special _root.tsx file in the ./src/pages directory that accepts a children prop of type ReactNode.

// ./src/pages/_root.tsx

// Create root element
export default async function RootElement({ children }) {
  return (
    <html lang="en">
      <head></head>
      <body data-version="1.0">{children}</body>
    </html>
  );
}

export const getConfig = async () => {
  return {
    render: 'static',
  };
};

Navigation

Link

The<Link /> component should be used for internal links. It accepts a to prop for the destination, which is automatically prefetched ahead of the navigation.

// ./src/pages/index.tsx
import { Link } from 'waku';

export default async function HomePage() {
  return (
    <>
      <h1>Home</h1>
      <Link to="/about">About</Link>
    </>
  );
}

useRouter

The useRouter hook can be used to inspect the current route or perform programmatic navigation.

router properties

The router object has two properties related to the current route: path (string) and query (string).

'use client';

import { useRouter_UNSTABLE as useRouter } from 'waku';

export const Component = () => {
  const { path, query } = useRouter();

  return (
    <>
      <div>current path: {path}</div>
      <div>current query: {query}</div>
    </>
  );
};

router methods

The router object also contains several methods for programmatic navigation:

• router.push(to: string) - navigate to the provided route

• router.prefetch(to: string) - prefetch the provided route

• router.replace(to: string) - replace the current history entry

• router.reload() - reload the current route

• router.back() - navigate to the previous entry in the session history

• router.forward() - navigate to the next entry in the session history

'use client';

import { useRouter_UNSTABLE as useRouter } from 'waku';

export const Component = () => {
  const router = useRouter();

  return (
    <>
      <button onClick={() => router.push('/')}>Home</button>
      <button onClick={() => router.back()}>Back</button>
    </>
  );
};

Metadata

Waku automatically hoists any title, meta, and link tags to the document head. That means adding meta tags is as simple as adding them to any of your layout or page components.

// ./src/pages/_layout.tsx
export default async function RootLayout({ children }) {
  return (
    <>
      <link rel="icon" type="image/png" href="/images/favicon.png" />
      <meta property="og:image" content="/images/opengraph.png" />
      {children}
    </>
  );
}

export const getConfig = async () => {
  return {
    render: 'static',
  };
};

// ./src/pages/index.tsx
export default async function HomePage() {
  return (
    <>
      <title>Waku</title>
      <meta name="description" content="The minimal React framework" />
      <h1>Waku</h1>
      <div>Hello world!</div>
    </>
  );
}

export const getConfig = async () => {
  return {
    render: 'static',
  };
};

Metadata can also be generated programmatically.

// ./src/pages/index.tsx
export default async function HomePage() {
  return (
    <>
      <Head />
      <div>{/* ...*/}</div>
    </>
  );
}

const Head = async () => {
  const metadata = await getMetadata();

  return (
    <>
      <title>{metadata.title}</title>
      <meta name="description" content={metadata.description} />
    </>
  );
};

const getMetadata = async () => {
  /* ... */
};

export const getConfig = async () => {
  return {
    render: 'static',
  };
};

Styling

Global styles

Install any required dev dependencies (e.g., npm i -D tailwindcss autoprefixer) and set up any required configuration (e.g., postcss.config.js). Then create your global stylesheet (e.g., ./src/styles.css) and import it into the root layout.

// ./src/pages/_layout.tsx
import '../styles.css';

export default async function RootLayout({ children }) {
  return <>{children}</>;
}

export const getConfig = async () => {
  return {
    render: 'static',
  };
};

/* ./src/styles.css */
@tailwind base;
@tailwind components;
@tailwind utilities;

// ./tailwind.config.js
export default {
  content: ['./src/**/*.{js,jsx,ts,tsx}'],
};

// ./postcss.config.js
export default {
  plugins: {
    tailwindcss: {},
    autoprefixer: {},
  },
};

Static assets

Static assets such as images, fonts, stylesheets, and scripts can be placed in a special ./public folder of the Waku project root directory. The public directory structure is served relative to the / base path.

// assuming image is saved at `/public/images/logo.svg`

export const Logo = () => {
  return (
    <>
      <img src="/images/logo.svg" />
    </>
  );
};

File system

Files placed in a special ./private folder of the Waku project root directory can be securely accessed in React server components.

export default async function HomePage() {
  const file = readFileSync('./private/README.md', 'utf8');

  return <>{/* ...*/}</>;
}

export const getConfig = async () => {
  return {
    render: 'static',
  };
};

Data fetching

Server

All of the wonderful patterns enabled by React server components are supported. For example, you can compile MDX files or perform code syntax highlighting on the server with zero impact on the client bundle size.

// ./src/pages/blog/[slug].tsx
import { MDX } from '../../components/mdx';
import { getArticle, getStaticPaths } from '../../lib/blog';

export default async function BlogArticlePage({ slug }) {
  const article = await getArticle(slug);

  return (
    <>
      <title>{article.frontmatter.title}</title>
      <h1>{article.frontmatter.title}</h1>
      <MDX>{article.content}</MDX>
    </>
  );
}

export const getConfig = async () => {
  const staticPaths = await getStaticPaths();

  return {
    render: 'static',
    staticPaths,
  };
};

Client

Data should be fetched on the server when possible for the best user experience, but all data fetching libraries such as React Query are compatible with Waku.

Mutations

Data mutations can be performed via server actions or API endpoints (coming soon).

Server actions

Server actions allow you to define and securely execute server-side logic directly from your React components without the need for manually setting up API endpoints, sending POST requests to them with fetch, or managing pending states and errors.

Defining and protecting actions

The 'use server' directive marks an async function as a server action. Waku automatically creates a reference to the action that can be passed as props or imported into client components, which can then call the referenced function.

When the directive is placed at the top of a function body, it will mark that specific function as an action. Alternatively, the directive can be placed at the top of a file, which will mark all exported functions as actions at once.

Be careful not to add the directive where inappropriate and inadvertently create unwanted endpoints. Endpoints created by server actions are not secured unless you add your own authentication and authorization logic inside the function body.

Making and consuming actions

When creating an inline server action within a server component, it can be passed as props to a client component.

// ./src/pages/contact.tsx

import db from 'some-db';

export default async function ContactPage() {
  const sendMessage = async (message: string) => {
    'use server';
    await db.messages.create(message);
  };

  return <ContactForm sendMessage={sendMessage} />;
}

// ./src/components/contact-form.tsx
'use client';

import { useState } from 'react';

export const ContactForm = ({ sendMessage }) => {
  const [message, setMessage] = useState('');

  return (
    <>
      <textarea
        value={message}
        onChange={(event) => setMessage(event.target.value)}
        rows={4}
      />
      <button onClick={() => sendMessage(message)}>Send message</button>
    </>
  );
};

When creating server actions in a separate file, they can be imported directly into client components.

// ./src/actions/send-message.ts
'use server';

import db from 'some-db';

export async function sendMessage(message: string) {
  await db.messages.create(message);
}

// ./src/components/contact-button.tsx
'use client';

import { sendMessage } from '../actions/send-message';

export const ContactButton = () => {
  const message = `Hello world!`;

  return <button onClick={() => sendMessage(message)}>Send message</button>;
};

Invoking actions

Actions can be invoked via event handlers such as onClick or onSubmit, as in the examples above, or in a useEffect hook, based on whichever conditions you choose.

They can also be invoked via an action prop on native <form> elements. In this case the server action will automatically receive a parameter of FormData with all of the form field values, including hidden ones.

// ./src/actions/send-message.ts
'use server';

import db from 'some-db';

export async function sendMessage(formData: FormData) {
  const message = formData.get('message');

  await db.messages.create(message);
}

// ./src/components/create-todo-button.tsx
'use client';

import { sendMessage } from '../actions/send-message';

export const ContactForm = () => {
  return (
    <form action={sendMessage}>
      <textarea name="message" rows={4} />
      <input type="hidden" name="secret-message" value="This too!" />
      <button type="submit">Send message</button>
    </form>
  );
};

If you must pass additional arguments to a form action beyond its native form fields, you can use the bind method to create an extended server action with the extra arguments.

// ./src/components/create-todo-button.tsx
'use client';

import { sendMessage } from '../actions/send-message';

export const ContactForm = ({ author = 'guest' }) => {
  const sendMessageWithAuthor = sendMessage.bind(null, author);

  return (
    <form action={sendMessageWithAuthor}>
      <textarea name="message" rows={4} />
      <button type="submit">Send message</button>
    </form>
  );
};

Enhancing actions

Server actions integrate with many other React APIs such as the useTransition hook for handling pending states, the useActionState hook for accessing returned values, and the useOptimistic hook for performing optimistic UI updates.

See the talk What’s new in React 19? to learn more.

State management

We recommend Jotai for global React state management based on the atomic model’s performance and scalability, but Waku is compatible with all React state management libraries such as Zustand and Valtio.

Environment variables

It’s important to distinguish environment variables that must be kept secret from those that can be made public.

Private

By default all environment variables are considered private and are accessible only in server components, which can be rendered exclusively in a secure environment. You must still take care not to inadvertently pass the variable as props to any client components.

Public

A special WAKU_PUBLIC_ prefix is required to make an environment variable public and accessible in client components. They will be present as cleartext in the production JavaScript bundle sent to users’ browsers.

Runtime agnostic (recommended)

Environment variables are available on the server via the Waku getEnv function and on the client via import.meta.env.

// server components can access both private and public variables
import { getEnv } from 'waku';

export const ServerComponent = async () => {
  const secretKey = getEnv('SECRET_KEY');

  return <>{/* ...*/}</>;
};

// client components can only access public variables
'use client';

export const ClientComponent = () => {
  const publicStatement = import.meta.env.WAKU_PUBLIC_HELLO;

  return <>{/* ...*/}</>;
};

Node.js

In Node.js environments, process.env may be used for compatibility.

// server components can access both private and public variables
export const ServerComponent = async () => {
  const secretKey = process.env.SECRET_KEY;

  return <>{/* ...*/}</>;
};

// client components can only access public variables
'use client';

export const ClientComponent = () => {
  const publicStatement = process.env.WAKU_PUBLIC_HELLO;

  return <>{/* ...*/}</>;
};

Deployment

Vercel

Waku projects can be deployed to Vercel with the Vercel CLI automatically.

vercel

Pure SSG

Adding the --with-vercel-static flag to the build script will produce static sites without serverless functions.

{
  "scripts": {
    "build": "waku build --with-vercel-static"
  }
}

Note: When rendering in static mode, please be sure to return render: 'static' from each of your page files' getConfig().

Netlify

Waku projects can be deployed to Netlify with the Netlify CLI.

npm run build -- --with-netlify
netlify deploy

Pure SSG

Adding the --with-netlify-static flag to the build script will produce static sites without Netlify functions.

{
  "scripts": {
    "build": "waku build --with-netlify-static"
  }
}

Note: When rendering in static mode, please be sure to return render: 'static' from each of your page files' getConfig().

Cloudflare (experimental)

npm run build -- --with-cloudflare
npx wrangler dev # or deploy

PartyKit (experimental)

npm run build -- --with-partykit
npx partykit dev # or deploy

Deno Deploy (experimental)

npm run build -- --with-deno
deployctl deploy --prod dist/serve-deno.js --exclude node_modules

AWS Lambda (experimental)

npm run build -- --with-aws-lambda

The handler entrypoint is dist/serve-asw-lambda.js: see Hono AWS Lambda Deploy Docs. Streaming can be activated by setting environment variable DEPLOY_AWS_LAMBDA_STREAMING=true npm run build -- --with-aws-lambda

Community

Please join our friendly GitHub discussions or Discord server to participate in the Waku community. Hope to see you there!

Roadmap

Waku is in active development and we’re seeking additional contributors. Check out our roadmap for more information.

Sponsors

Thanks to all our wonderful sponsors.