what
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What Documentation

Build server-rendered web apps with HTML. No JavaScript frameworks, no build steps, no boilerplate.

What is the What framework?

The What framework is a Rust-powered web framework where you write HTML pages instead of backend code. Variables use #hash# syntax, components are plain HTML files, and interactivity works through declarative attributes.

<h1>Hello, #user.name#!</h1>
<p>You have #session.notifications# new notifications.</p>

<button w-set="session.notifications = 0">Mark all read</button>

That's a complete interactive page. The session variable updates on click, and every element showing #session.notifications# updates automatically.

How It Works

The What framework follows a simple model:

  • Pages are HTML files in the site/ directory. File paths become routes.
  • Variables use #name# syntax. Session, user, environment, and fetched data are all available.
  • Components are HTML files in components/. The file card.html becomes <what-card>.
  • Interactivity uses w-* attributes: w-get, w-set, w-modal-trigger, etc.
  • Forms handle CRUD operations with w-action="create" and server-side validation.
  • Data comes from local collections, external APIs, or Cloudflare D1.

Quick Example

A todo app in one file:

site/todos.html
<what>
auth: user
fetch.todos = "local:todos"
</what>

<h1>My Todos</h1>

<form w-action="create" w-store="todos" w-validate>
  <input name="title" w-required placeholder="What needs doing?">
  <button type="submit">Add</button>
</form>

<loop data="#todos#" as="todo">
  <div class="flex items-center gap-3">
    <span>#todo.title#</span>
    <form w-action="delete" w-store="todos" w-id="#todo.id#">
      <button type="submit" w-confirm="Delete this todo?">Delete</button>
    </form>
  </div>
</loop>

This gives you: authentication, form validation, CRUD operations, data fetching, and confirmation dialogs — all from HTML.

Philosophy

  • HTML is enough. If you know HTML and CSS, you can build full-stack web apps.
  • Zero JavaScript by default. All interactivity is declarative. Write JS only when you want to.
  • Convention over configuration. File-based routing, auto-discovered components, sensible defaults.
  • Progressive complexity. Start with a static page, add session state, then forms, then databases — one concept at a time.

Next Steps

Start with Getting Started to install What and create your first project, or jump to any topic in the sidebar.

Next → Getting Started