Hi everyone,

I’ve been working on Francis, a lightweight framework built on top of Plug and Bandit that tries to get you from idea to a running endpoint with as little ceremony as possible. Think Sinatra for Elixir.

What it is

You use Francis in a module, define routes with get/post/ws/sse, and you have a running server. No routers, no controllers, no context boilerplate, just a function per route.

defmodule MyApp do
  use Francis

  get "/", fn _ -> %{hello: :world} end
  get "/:name", fn %{params: %{"name" => name}} -> "hello #{name}" end
  post "/", fn conn -> conn.body_params end

  ws "/chat", fn
    :join, socket -> {:reply, "welcome"}
    {:received, msg}, _ -> {:reply, msg}
  end

  sse "/events", fn
    :join, socket -> {:reply, %{id: socket.id}}
    {:received, m}, _ -> {:reply, m}
  end

  unmatched fn _ -> "not found" end
end

Return a string and it renders as HTML. Return a map and it renders as JSON. Return a Plug.Conn for full control.

Get started

mix archive.install hex francis
mix francis.new my_app
cd my_app
mix francis.server

Or add to an existing project:

{:francis, “~> 0.3”}

If you use Claude Code, install the Francis skill for route patterns, SSE/WS gotchas, and security guidance:

npx skills add francis-build/francis@francis-thinking

Links

• Hex: francis | Hex
• Docs: Francis v0.3.3 — Documentation
• Site: https://francis.build

Curious what the community thinks. It is not trying to replace Phoenix, it is for when you want something closer to raw Plug without writing the same boilerplate every time. Happy to answer questions.