ContactHub is a secure, federated contact information sharing service designed to protect your privacy. By using the ActivityPub protocol, ContactHub allows you to host your own server and share your contact information with others in a decentralized manner. Websites like Amazon, online shops, or any other site requiring address information can use our OAuth integration to securely access user contact information, automatically updating it when a user modifies their details.


  • Decentralized and federated architecture
  • Privacy-focused: Users control who can access their contact information
  • ActivityPub protocol support
  • OAuth integration for seamless third-party access
  • International-friendly address format
  • Open-source and customizable


Detailed documentation is available to help you understand the ContactHub architecture, protocol, and implementation. Here are the main sections of the documentation:

  • Actors: Learn about the different types of actors in the ContactHub system.
  • Activities: Understand the various ActivityPub activities used for sharing and requesting contact information.
  • Objects: Discover the structure of the ContactInfo object and how it is used in ContactHub.
  • Protocol: Get an overview of the ActivityPub protocol implementation in ContactHub.


ContactHub can be implemented in various programming languages, allowing you to choose the most suitable language for your server. Check out the available implementations and follow the instructions in their respective README files:

  • Rust

Example Instance

Try out ContactHub with our example instance hosted at This instance allows you to experience the features and functionality of ContactHub without having to set up your own server.


We welcome contributions to the ContactHub project! If you have any suggestions, bug reports, or feature requests, please open an issue on the GitHub repository. If you'd like to contribute code or documentation, feel free to submit a pull request.


ContactHub is released under the GNU Affero General Public License v3.0. This is the same license used by Mastodon.

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