Dialup is a WebSocket-first, file-based routing framework for Elixir.

Each browser tab gets its own Elixir process (an internal UserSessionProcess), and all user interactions flow through that process via WebSocket. The server renders HTML and sends it to the client, where idiomorph morphs the DOM efficiently.

Setup

Add use Dialup to your Application module:

defmodule MyApp do
  use Application

  use Dialup,
    app_dir: __DIR__ <> "/app",
    title: "My App",
    lang: "en"

  @impl Application
  def start(_type, _args) do
    children = [{Dialup, app: __MODULE__, port: 4000}]
    Supervisor.start_link(children, strategy: :one_for_one, name: MyApp.Supervisor)
  end
end

Options for use Dialup

• :app_dir — (required) path to the directory containing page.ex / layout.ex files. Typically __DIR__ <> "/app".
• :title — default <title> value used when page_title/1 returns nil. Defaults to "Dialup App".
• :lang — value for the html lang attribute. Defaults to "en".
• :check_origin — WebSocket origin validation. :conn (default) validates against the HTTP host, false disables validation, or a list of allowed hosts.
• :agent_session — when true, enables POST /_dialup/agent-session for headless MCP sessions. Defaults to false; opt in explicitly and protect with auth plugs in production.
• :secure_cookies — sets the Secure flag on dialup_session cookies. :auto (default) enables it when the request is HTTPS (conn.scheme or X-Forwarded-Proto: https); true or false force the flag on or off.
• :plugs — list of additional Plug modules inserted into the HTTP pipeline (e.g. auth).
• :auth_accounts — module implementing Dialup.Auth.Accounts for user resolution.
• :session_store — :memory (default) or :ets. Use :ets to persist session state across process restarts.

Child spec

Dialup implements child_spec/1 and start_link/1, so you can add it directly to a supervision tree:

children = [{Dialup, app: MyApp, port: 4000}]

File-based routing

Files placed under app_dir are automatically compiled into a route table at build time:

app/
├── layout.ex        # root layout
├── page.ex          # route: /
├── error.ex         # error page
└── blog/
    ├── layout.ex    # nested layout for /blog/*
    └── [slug]/
        └── page.ex  # route: /blog/:slug (dynamic)

No router.ex registration is required.