IPB

A powerful, free, open-source Internet forum package written in PHP. phpBB offers a wide range of features including customizable themes, extensive user management, private messaging, search functionality, and multi-language support. It's known for its robust security measures and active community of developers who continually contribute to its improvement. phpBB is highly extensible through plugins and modifications, making it suitable for a variety of community sizes and types, from small hobby groups to large corporate forums.

A commercial PHP-based forum hosting program designed for deployment on remote web servers. XenForo is known for its modern, responsive design and user-friendly interface. It offers features like advanced permissions system, powerful search functionality, and integrated content management. XenForo includes built-in spam prevention tools, a flexible addon system, and comprehensive theming capabilities. Its focus on performance and scalability makes it popular among larger communities and businesses requiring a robust forum solution.

A free, open-source forum software written in PHP. SMF offers a good balance of features and simplicity, including customizable themes, member groups, and moderation tools. It provides built-in search functionality, a package manager for easy installation of modifications, and support for multiple languages. SMF's user-friendly administration panel and active community make it a popular choice for small to medium-sized communities looking for a reliable, easy-to-manage forum solution.

Reddit is a massive social news aggregation, web content rating, and discussion platform. It allows users to submit content and participate in discussions organized into user-created "subreddits". Reddit's unique voting system, where users can upvote or downvote content, helps surface popular content. Its API and extensive moderation tools make it a powerful platform for building large-scale online communities around specific topics or interests.

An open-source internet forum and mailing list management software application that aims to modernize traditional forum software. Discourse features a clean, mobile-responsive design and emphasizes user engagement through features like infinite scrolling, real-time updates, and gamification elements. It offers robust moderation tools, SSO integration, and extensive API support. Discourse's unique approach to forum discussions, including its topic summarization feature and trust level system, makes it particularly suitable for communities looking for a more dynamic and interactive forum experience.