Federated Social Networks Using ActivityPub

Mastodon is a self-hosted, decentralized social networking platform that functions as a microblogging application. It enables independent server instances to communicate and exchange social data through the standardized ActivityPub protocol, allowing users to participate in a global, interoperable network. The platform distinguishes itself through its federated architecture, which grants administrators full control over their community instances. This includes comprehensive tools for user moderation, account management, and the enforcement of community guidelines. The system is designed to handle high-traffic environments, utilizing background processing for heavy tasks and persistent connections to deliver real-time updates and notifications to users. Beyond its core social features, the platform provides a robust administrative surface for managing server identity, network security, and infrastructure scaling. It supports complex content discovery through optional external search engine integration and offers a comprehensive API for managing accounts, statuses, media attachments, and server-wide announcements. The software is configured primarily through environment variables, allowing for flexible deployment across diverse hosting environments. Administrative tasks, including system maintenance and user management, are supported through a command-line interface.

Misskey is a self-hosted, decentralized microblogging platform and federated social media server. It functions as a distributed content management system that allows users to communicate across multiple independent and interconnected server instances using the ActivityPub protocol. The platform distinguishes itself with a dynamic application engine that allows for the creation of interactive applications and custom page layouts using a scripting language. It also features a specialized markup language for rich text rendering, enabling the use of animations and custom styles for consistent content presentation. The system provides comprehensive capabilities for community management, including role-based access control, content moderation tools, and private messaging with configurable acceptance rules. It also includes full-text search for posts and profiles, server performance monitoring via interactive charts, and administrative command-line tools for system maintenance. Users can secure their accounts using multi-factor authentication and passkeys, while administrators can manage the infrastructure through schema-based database migrations and orchestrated caching services.

Pixelfed is a decentralized, self-hosted photo sharing platform and social network. It uses the ActivityPub protocol to enable federation, allowing independent server instances to share user profiles, media, and posts across a distributed network. The platform distinguishes itself with a focus on media portability and processing, featuring tools for importing content from Instagram and utilizing client-side WebGL for image filter processing. It employs a driver-based storage abstraction to manage media across local disks or S3-compatible cloud object storage. The system includes capabilities for content organization through custom portfolios, trending content discovery, and community moderation tools such as automated spam detection. User identity is managed via role-based access control and support for external identity providers. Deployment is supported through containerized images and Docker Compose orchestration, with additional distribution support for YunoHost.

Lemmy is a self-hosted, federated discussion platform that enables the operation of independent, decentralized social networking servers. By implementing the ActivityPub protocol, it allows autonomous instances to exchange content, synchronize user interactions, and participate in a global, distributed network without centralized control. The platform distinguishes itself through a decoupled architecture that separates the backend API from the frontend, facilitating the development of custom interfaces while maintaining unified user handles and cross-platform communication. It provides granular administrative and moderation tools, including public action auditing, role delegation, and the ability to manage federated connections, which allows administrators to enforce local community standards across the broader network. The system supports a comprehensive suite of social features, including threaded conversations, content voting, and hierarchical discussion management. It is designed for scalability, utilizing asynchronous background processing and horizontal service partitioning to handle federation workloads and traffic efficiently. Administrators can further secure and customize their instances through integrated traffic controls, language filtering, and support for anonymous network routing. The project provides containerized deployment workflows and automated database migration management to simplify the maintenance of self-hosted environments.

This project provides a comprehensive implementation of the AT Protocol, serving as a framework for building decentralized social networking applications. It enables the creation of distributed data repositories where users maintain cryptographic ownership of their identity and content, allowing for portable accounts that can be migrated between independent servers without central authority intervention. The platform distinguishes itself by decoupling content hosting from discovery through modular algorithmic curation. Users can select third-party services to filter and organize their feeds, while content moderation is handled through a flexible labeling system that allows for both automated and community-driven content standards. By utilizing content-addressed storage and cryptographically signed records, the system ensures that data integrity can be independently verified across the network. Beyond core identity and storage, the project includes infrastructure for real-time network event streaming, media distribution, and global data aggregation. It supports complex social interactions through automated agents and provides tools for managing distributed repository state, including historical data backfilling and scalable traffic management. The repository contains the necessary tools and services to interact with the federated network, including standardized authentication flows and schema-based data interoperability.

Diaspora is a federated social networking platform that allows users to run and manage self-hosted community servers, known as pods. It operates as a distributed network where independent server nodes exchange content and users using open protocols and standardized communication schemas. The platform is distinguished by its focus on decentralized identity management and privacy-preserving communication. It includes a privacy-focused media proxy that routes external assets through a local server to protect user identity and supports cross-instance account migration, allowing users to move their profiles and social history between different network nodes. The system provides a comprehensive set of social tools, including markdown publishing, multi-language support with right-to-left text direction, and private messaging. Administrative capabilities cover content moderation, role-based access control, and automated account maintenance, while security is handled through two-factor authentication and OpenID identity integration. The platform provides a public JSON endpoint for monitoring pod statistics and versioning.

Writefreely is an open-source, multi-tenant publishing server and blogging engine. It provides a decentralized system for hosting minimalist blogs, utilizing the ActivityPub protocol to federate content and identities across different servers and social networks. The platform focuses on a distraction-free writing experience by removing social metrics and providing an auto-saving editor. It allows a single user account to manage multiple distinct blogs and pen names, maintaining separate writing personas within one installation. The system includes tools for content organization through hashtag categorization, post scheduling, and navigation pinning. Authors can customize the visual presentation of their blogs using custom CSS. Additionally, the software supports collective publication spaces, community content moderation, and multilingual script support for non-Latin and right-to-left text. The service is written in Go and uses PostgreSQL for persistent data storage.

PeerTube is a decentralized, open-source video hosting platform that enables users to operate independent, interoperable servers. By utilizing the ActivityPub protocol, it connects these servers into a global, federated network where users can follow channels, discover content, and interact across different instances. The platform is designed to function as a self-hosted video content management system, providing a community-driven alternative to centralized media services. What distinguishes PeerTube is its hybrid approach to content delivery and infrastructure management. It integrates peer-to-peer distribution via WebTorrent to reduce server bandwidth consumption, while simultaneously supporting remote object storage to decouple media assets from local disk capacity. To maintain performance under high load, the platform delegates resource-intensive tasks like video transcoding and transcription to external worker instances, ensuring the primary server remains responsive. The platform offers a comprehensive suite of tools for content management, including live streaming, automated moderation, and granular access controls. Its extensibility is supported by a hook-based plugin architecture, allowing administrators to inject custom logic, modify interface elements, or integrate third-party services. Additionally, the system provides a robust command-line interface and a standardized REST API, enabling programmatic control over administrative tasks, bulk content processing, and platform maintenance. The software is packaged for containerized deployment, simplifying infrastructure management and ensuring consistent execution across various hosting environments.

NodeBB is a real-time, self-hosted community forum platform built on Node.js. It is designed to support scalable discussion environments by utilizing a document-oriented database for content storage and an in-memory engine for high-speed data retrieval and session management. The platform provides a comprehensive administrative interface for managing user groups, forum settings, and system health. What distinguishes the platform is its native support for federated social networking via the ActivityPub protocol, allowing forums to exchange content, synchronize discussions, and interact with decentralized platforms across the fediverse. It features a highly modular architecture that relies on an event-driven plugin system, enabling administrators to inject custom logic, modify data flows, and extend functionality through themes and server-side hooks. The platform includes a robust suite of operational tools for managing the full application lifecycle, including automated system upgrades, process health monitoring, and multi-process scaling to handle concurrent traffic. It also offers extensive customization options for the user interface, including dynamic template rendering, widget management, and support for multi-language localization. The software is designed for deployment across diverse environments, supporting containerized setups and various cloud platforms. It includes built-in mechanisms for database backups, asset archiving, and traffic orchestration through reverse proxy integration.