Forem Project Structure
The open-source software for building modern communities. A feature-rich Ruby on Rails monolith using Preact for its interactive frontend components.
Updated 2025-12-30
Project Directory
Repository Info
- Repository-forem/forem
- Stars-20k+
- License-AGPL-3.0
- Last Analyzed-December 2025
Tech Stack
- Backend-Ruby on Rails
- Frontend-Preact + TypeScript
- Database-PostgreSQL
- Cache-Redis
- Search-Algolia / Elasticsearch
- Design System-Crayons (Custom)
Architecture Notes
Forem is a mature, content-driven monolith. It follows standard Rails conventions but introduces a significant **Service Layer** (app/services/) to keep models and controllers lean. A standout feature is the **Liquid Tags** system, which provides a secure and extensible way to embed rich content from dozens of external platforms directly into user posts. The frontend is a hybrid, using Rails views for layout and **Preact** for highly interactive components.
Key Directories
- app/liquid_tags/-Contains the implementation for every embed type supported by Forem. Each tag defines how to parse user input and render the resulting HTML/Preact component.
- app/services/-Where the 'heavy lifting' happens. Includes feed ranking algorithms, notification dispatching, and user onboarding flows.
- app/javascript/-The home of the modern frontend. Built with Preact, it handles everything from the article editor to real-time chat and notifications.
Why This Structure?
Forem is the engine behind dev.to and many other developer communities. Its codebase is an excellent example of a high-scale Rails application that has successfully integrated a modern JavaScript framework.