Concordia is a live, multi-user terminal sharing tool for interactive TUI apps.

Think of it like Google Docs for terminal sessions: one host runs a program, other users join with an invite link, and everyone sees the same live screen and can collaborate in real time.

• Internet-first collaboration with invite codes (no manual SSH account setup per guest).
• One host-managed runtime for quick pair/mob sessions.
• Shared live view for all participants, including the host's own terminal stream.
• Better for ad-hoc collaborative sessions than managing remote shell access and key distribution.

Use tmux/ssh when you want full server administration and long-lived personal shells. Use Concordia when you want fast collaborative live sessions.

1. Install:

bash install.sh

2. Set ngrok auth token on the host (required):

export NGROK_AUTHTOKEN=YOUR_NGROK_TOKEN

3. Start a party and choose the shared program:

concordia_host --program "bash"

4. Share the invite code printed by host.

5. Join from another machine:

concordia_client <paste-invite-code> --user alice

Any interactive terminal program that runs on the host, for example:

• bash, zsh, fish
• python3 -q, ipython
• htop, btop
• vim, nvim
• lazygit
• custom internal TUIs

# Share a shell
concordia_host --program "bash"

# Share a Python REPL in a specific project
concordia_host --project-dir ~/my-project --program "python3 -q"

# Share a TUI app
concordia_host --program "lazygit"

# Join
concordia_client concordia://<ngrok-host>:<ngrok-port>/<token> --user bob

• Host starts a websocket server and launches the chosen program inside a PTY.
• Clients connect with invite token.
• Client input bytes are forwarded to host PTY stdin.
• PTY output bytes are broadcast to all connected clients.
• Control messages (invite, participants, system, error) are sent as JSON.

• Python 3.9+ on host and clients
• ngrok auth token on host (NGROK_AUTHTOKEN)
• The shared program installed on host and available on PATH

pipx install .

If you do not use pipx:

python3 -m pip install --user .

• Host command: concordia_host
• Client command: concordia_client
• Use --plain for legacy non-TUI mode.

• --program is required when creating a party.
• --project-dir sets the working directory for the shared program process.
• --no-local-repl runs server without auto-connecting host client.
• ngrok is required for hosting; invite host/port come from the ngrok tunnel.
• --public-host and --ngrok are deprecated and ignored.

docker build -t concordia .
docker run --rm -it \
  -p 8765:8765 \
  --env NGROK_AUTHTOKEN=YOUR_NGROK_TOKEN \
  concordia \
  concordia --create-party --host 0.0.0.0 --program "bash"

Or:

docker compose up --build

Join from another machine:

concordia_client concordia://<ngrok-host>:<ngrok-port>/TOKEN --user alice

./scripts/build_bundle.sh
./dist/concordia.pyz --create-party --program "bash"

./scripts/build_release.sh

Upload artifacts in dist/ to GitHub Releases.