Simple Machines Forum
Free, open-source PHP forum software with multiple database backends.
752 stars 268 forks last commit first released
Actively maintained
Last commit 25 Aug 2026.

Simple Machines Forum (SMF) is an open-source bulletin board software written in PHP. It provides a scalable, feature-rich platform to run online communities with forums, topics, user roles, moderation, and a modular addon system.
Key Features
- Uses PHP and MySQL, PostgreSQL, or SQLite for data storage.
- Newly developed template system to simplify customization and theming.
- Advanced permissions and multi-language support for diverse communities.
- Package Manager to install/uninstall mods and themes with a few clicks.
- Rich posting features including WYSIWYG editing, BBCode, spell check, and attachments.
- Moderation tools and a dedicated moderation center for staff workflows.
- Attachments, polls, calendars, and RSS/XHTML outputs for rich content and engagement.
- External integration via SSI to embed recent topics, polls, and news into other websites.
- Open-source with well-documented source code and community-driven enhancements.
Use Cases
- Build a public or private forum for a community or business with multi-board structure and granular permissions.
- Embed forum content into an existing website using SSI to display recent topics, polls, or news.
- Run a moderated community with attachments, polls, and calendars to coordinate events and discussions.
Limitations and Considerations
Conclusion
SMF offers a mature, lightweight forum solution with a modular extension system and broad database support, suitable for small to mid-sized online communities.
Categories:
Tags:
Tech Stack:
Similar to Simple Machines Forum

Flarum
Open-source PHP forum software for building communities
Lightweight, extensible forum platform built in PHP with a Mithril.js frontend, supporting MySQL/MariaDB/PostgreSQL/SQLite and an active extensions ecosystem.
MyBB
Free, open-source forum software for managing online communities
MyBB is a PHP-based, open-source forum platform with plugins, themes, moderation tools, private messaging and multi-database support.

Grav
Flat-file PHP CMS using Markdown, Twig and YAML
Open-source flat-file CMS for PHP that uses Markdown, Twig templates and YAML configs with a package manager for fast, flexible sites.
Expressa
Data-driven API middleware with an admin UI for Express.js
Express middleware that generates REST collection APIs from JSON Schema with a Django-like admin UI; supports MongoDB, PostgreSQL or JSON-file storage.
Dotclear
Open-source PHP blogging and web-publishing platform
A lightweight open-source PHP blog engine with multilingual support, themes/plugins, media manager, and multi-database compatibility (MySQL, MariaDB, PostgreSQL, SQLite).

Discourse
Modern discussion forum and community platform
Discourse is open-source forum software for community discussion, support, and knowledge sharing, with moderation tools, customization, and built-in chat.
