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Simple Machines Forum

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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 screenshot

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.

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