---
title: "The Boundary ActiveAdmin Forces: HTML Admin vs API Controllers"
description: "ActiveAdmin needs a full Rails web boundary, while API-only endpoints need a lean controller. Compare the two paths to see where sessions, assets, and browser protections belong."
---
# The Boundary ActiveAdmin Forces: HTML Admin vs API Controllers
**Type:** [Comparison](https://yomu.fyi/visual-explainers/category/comparison.md)
> ActiveAdmin needs a full Rails web boundary, while API-only endpoints need a lean controller. Compare the two paths to see where sessions, assets, and browser protections belong.
## Explanation
ActiveAdmin provides CMS capabilities inside a Rails application, but it needs HTML views, cookies, flash messages, sessions, middleware, and assets that API-only mode omits. The practical split is a full ActionController::Base path for the admin surface and a separate ApiController that retains ActionController::API. This comparison helps engineers keep browser concerns explicit without weakening API endpoints.
**Tags:** [ActiveAdmin](https://yomu.fyi/topic/activeadmin.md), [API](https://yomu.fyi/topic/api.md), [Architecture](https://yomu.fyi/topic/architecture.md), [JavaScript](https://yomu.fyi/topic/javascript.md), [Ruby on Rails](https://yomu.fyi/topic/ruby-on-rails.md)
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