Backdrop CMS

Backdrop CMS is a lightweight, self‑hosted content management system that emerged as a fork of Drupal. It targets developers who want a familiar PHP‑based architecture but with a tighter focus on rapid learning and out‑of‑the‑box functionality. From a technical standpoint, Backdrop is a modular monolith: the core provides routing, request handling, and a pluggable entity‑storage system, while most features are added via contributed modules that expose well‑defined APIs. The system is built on PHP 7.1+, MySQL (or MariaDB) with PDO, and runs natively on Apache or Nginx. The codebase is intentionally slimmed compared to Drupal 8/9, removing the heavy Symfony dependencies and instead using a custom lightweight framework that mimics Drupal 7’s procedural style with optional object‑oriented extensions.

Architecture

• Language & Runtime: PHP 7.1+ (recommended), leveraging native PDO for database access.
• Framework: A custom MVC‑like layer that combines procedural hooks (hook_*) with service objects. This hybrid model allows developers to write simple PHP functions or full OOP services without leaving the core API.
• Database: MySQL 5.5+ (or MariaDB) with a single backdrop schema that stores entities, configuration, and file metadata. The entity system supports flexible field types and revisioning similar to Drupal 7.
• Web Server: Apache (with mod_rewrite) or Nginx (with fastcgi). URL rewriting is handled by a .htaccess file or an Nginx location block, providing clean permalinks out of the box.
• Template Engine: PHP’s native templating with optional integration of Twig for more advanced theming. Themes are composed of .tpl.php files and CSS/JS assets, allowing developers to override templates with minimal effort.

Core Capabilities

• Entity API: Create, read, update, delete (CRUD) operations for nodes, users, taxonomy terms, and custom entities. Developers can extend the API by defining new entity types in a module’s module_name.info.yml and implementing hook functions.
• Hook System: The classic Drupal‑style hooks (hook_menu, hook_form_alter, etc.) enable deep customization without modifying core code. This event‑driven approach keeps the system loosely coupled.
• Configuration Management: JSON‑based config files that can be exported/imported, facilitating version control of site settings.
• REST and JSON‑API: Built‑in RESTful endpoints expose entities, with optional authentication (basic, OAuth2) and JSON‑API compliance for headless use cases.
• Webhooks & API: Modules such as webhook allow outbound HTTP callbacks on entity events, while the service module exposes a SOAP/REST interface for external integration.

Deployment & Infrastructure

Backdrop is designed to run on shared hosting, but it scales gracefully in Docker or Kubernetes environments. A single Dockerfile builds the image from a base PHP-FPM container, and official Docker Compose files are available for quick local development. For production, Backdrop benefits from caching layers (e.g., Varnish, Redis) and CDNs; the project already partners with Fastly for its own traffic. The lightweight core keeps memory usage below 150 MB, making it suitable for low‑resource VPS or cloud instances. Horizontal scaling is achieved by sharing a single database across multiple web servers, while file uploads are stored in a shared filesystem or object storage (S3-compatible) via the file module.

Integration & Extensibility

• Module Ecosystem: Over 300 contributed modules cover SEO, e‑commerce (Commerce), media handling, and more. Each module follows the same hook conventions, making it trivial to write custom modules that plug into existing workflows.
• API & Webhooks: The RESTful API and webhook system enable integration with external services (e.g., Slack, Zapier) or custom microservices. Developers can write PHP classes that implement Backdrop\Core\Plugin interfaces to expose new endpoints.
• Theme System: Themes can override core templates, CSS, and JavaScript. The templating layer supports dynamic asset aggregation, minimizing HTTP requests.
• CLI Tools: drush‑compatible commands (backdrop-cron, backdrop-migrate) provide a command‑line interface for routine tasks, making CI/CD pipelines straightforward.

Developer Experience

Backdrop’s documentation is organized around the core API and module development, with clear examples and a “Contribute to Backdrop Core” guide that walks through pull‑request workflows. The community is active on GitHub, Discord, and the Backdrop forums, offering rapid feedback for bug reports or feature requests. Licensing is GPLv2+, ensuring that any derivative work remains open source. Because Backdrop keeps the codebase lean, developers can inspect the core logic quickly and contribute without grappling with Symfony bundles or Composer dependencies.

Use Cases

• Rapid Prototyping: Build a blog, portfolio, or small intranet in days thanks to the pre‑built entity system and theme engine.
• Headless CMS: Expose content via JSON‑API for mobile or SPA frontends, leveraging Backdrop’s lightweight PHP runtime.
• Shared Hosting Deployments: Deploy on low‑cost cPanel or Plesk environments where PHP and MySQL are already available.
• Custom Enterprise Sites: Extend Backdrop with custom modules for workflow, multi‑site management, or integration with legacy systems.

Advantages

• **Performance &