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Tandem is a decentralized, collaborative text-editing solution. Tandem works with native text editors, works across different editors, and uses peer-to-peer connections to facilitate communication.

Tandem exists as a set of plugins for native text editors. We currently support Sublime Text 3 and Neovim. We also unofficially support Vim.

Collaborating is as easy as installing the plugin on your editor and creating a Tandem Session. Invite other people to your session, and get typing in tandem!



Tandem is currently supported on Mac OS X - it may work on Linux, but use at your own risk.
To use Tandem, your environment must have python3.6+ and node.js installed (tested and confirmed working on node.js v7.7.4).
python3.6+ is a requirement for our agent code and node.js is required by our CRDT.


Please follow the installation guides for your plugin of choice:

How it Works

Tandem is split into four components: the editor plugins, the networking agent, the conflict-free replicated data type (CRDT) solution, and the rendezvous server.

Editor Plugins

The plugins interface with the text buffer in your plugin, detecting local changes and applying remote changes, and allowing users to create, join and leave sessions. Each plugin has its own repository and code.


The agent establishes connections between other peers connected to your collaborative session. It takes messages from the editor plugin and broadcasts them to all peers, and with the help of the CRDT instructs the editor to apply remote changes to your local text buffer.


The CRDT is used to represent the state of your local document, and transforms document edits into operations that can be applied remotely, without conflicts. We submit these conflict-free operations to other peers via the agent.

Instead of reinventing the wheel and writing the CRDT ourselves, we leveraged the work done by GitHub's team working on Teletype. We used their CRDT under the hood and instead focussed our efforts on integrating the CRDT with different editors.

Rendezvous Server

The rendezvous server is used to help establish peer-to-peer connections. It server notes the connection details of any peer that joins a session. When any subsequent peer wants to join, the server provides the connection details of all other peers in the session so that they can communicate directly with each other.

Note: Peer-to-peer connections cannot always be established. As a convenience to the user, the rendezvous server will also act as a relay to send data between agents when this happens.
If you wish to disable this behaviour, you can do so by disabling the USE_RELAY flag in: agent/tandem/agent/

Terms of Service

By using Tandem, you agree that any modified versions of Tandem will not use the rendezvous server hosted by the owners. You must host and use your own copy of the rendezvous server. We want to provide a good user experience for Tandem, and it would be difficult to do that with modified clients as well.

You can launch the rendezvous server by running python3 ./rendezvous/ Change the address of the rendezvous server used by the agent in the configuration file to point to your server's host. This file is located at: agent/tandem/agent/


Copyright (c) 2018 Team Lightly


Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at:


Team Lightly
Geoffrey Yu, Jamiboy Mohammad and Sameer Chitley

We are a team of senior Software Engineering students at the University of Waterloo.
Tandem was created as our Engineering Capstone Design Project.