Lean CMS — A lightweight Rails CMS with in-context editing — Lightweight Rails CMS with in-context editing

Why Lean CMS

Built for the dev who'd rather write Rails than wrestle WordPress.

Marketing sites are read-heavy and design-driven. Lean CMS optimizes for both — without taking your layout hostage or running its own database server.

In-context editing

Editors hover over any page section to reveal an Edit overlay. No back-and-forth between admin and live preview — the live page is the editor.

Your design, untouched

Lean CMS provides helpers to pull content into your ERB templates. It never injects a theme, never wraps your markup, never owns your layout.

SQLite-first

No database server to run, no add-on bill. A single file deployable with Kamal — production-ready for marketing sites at any reasonable scale.

In action

Hover. Edit. Done.

Editors don't context-switch into a separate admin to make a change. They click directly on the text, image, or section overlay — and a focused editor appears, right where the content lives.

Lean CMS in-context editing on the live page: hovering the hero subheading reveals floating Edit and Undo buttons next to the text, with a dashed outline showing the editable region — Hovering over the live page reveals inline Edit / Undo controls.

The Edit Text modal opened against the dimmed page: a textarea pre-populated with the current subheading, Cancel and Save buttons, with the surrounding page still visible behind — Clicking opens a focused edit modal. The page stays in view.

A taste

This is the whole API.

Drop helpers into your views. Logged-in editors get an overlay; visitors see plain, unwrapped HTML.

<%# A hover-editable section %>
<%= cms_editable_section(page: "home", section: "hero") do %>
  <section class="hero">
    <h1><%= editable_content("hero", "heading") %></h1>
    <p><%= editable_content("hero", "subhead") %></p>

    <% bg = page_content_image_url(@page, "hero", "bg") %>
    <% if bg %>
      <%= image_tag bg, class: "absolute inset-0" %>
    <% end %>
  </section>
<% end %>

<%# Optimized responsive image, gem-managed %>
<%= lean_cms_picture_tag "hero",
      alt: "Hero photo",
      widths: [640, 1280],
      sizes: "(min-width: 768px) 50vw, 100vw" %>

One layer of indirection. That's it.

Every helper does one obvious thing. You can read the source of every public method in five minutes.

cms_editable_section — wraps a block in a hover-edit overlay for admins
editable_content — inline-editable text fields
page_content_image_url — ActiveStorage image with optional variants
cards_section / bullets_section — list components admins can reorder
lean_cms_picture_tag — responsive <picture> with WebP+fallback

What you get

Everything a marketing site needs.
Nothing it doesn't.

Lean CMS admin Page Content editor — left sidebar nav, expanded Home page showing Hero Section, Statistics, Services Preview, and Call to Action with field counts and last-edited timestamps

9 content types

text, rich text, image, boolean, url, color, dropdown, cards, bullets.

Built-in auth

Version history

Every content change tracked via PaperTrail. One-click undo on inline edits.

Image optimizer

Rake task that emits WebP + JPG fallback variants at multiple widths.

Role-based access

Granular permission flags: pages, blog, users, settings. Plus super admin.

Content sync

Pull production content locally to stage changes; deploy via migrations.

Form submissions

Define forms in YAML; submissions land in the admin with email notifications.

YAML-defined structure

Declare pages, sections, fields in config/lean_cms_structure.yml; seed in one task.

Roadmap

From engine, to generator, to site builder.

Lean CMS today is a Rails engine you drop into an app. The plan is to grow into a full app generator and, eventually, a hosted site-builder service.

Today

Rails engine

In-context editing, auth, content types, image optimization in any Rails 8 app.

App generator

lean_cms new my-site --structure=site.yml — full Rails app from a YAML spec.

Later

Hosted site builder

Intake form → AI-generated YAML → app generation → Kamal deploy to a fresh droplet.

Ready in five commands.

From bundle install to /lean-cms/login in under a minute.

$ bundle add lean_cms && rails generate lean_cms:install && rails db:migrate

Read the installation guide View on GitHub