So I built jmux. It turns tmux into a parallel development environment. Every session, every agent, every running process, visible and navigable from one terminal. When Claude Code completes a response, an orange flag appears on that session. Switch to it, review the work, move on. No context switching to a different app. No learning a new workflow. It's still tmux underneath.
The key decision was to build on tmux instead of replacing it. My ~/.tmux.conf still works. My neovim setup still works. My keybindings, plugins, prefix key, etc, all of it carries over. jmux just makes it all work at scale.
What it does:
- Run Claude Code, Codex, aider. Any agent, directly, in parallel
- Attention flags. Know the moment an agent finishes without watching every pane
- Instant switching between sessions (Ctrl-Shift-Up/Down, no prefix key)
- Auto-groups sessions by project and git branch
- Works with your existing tmux config, editor, and tools
- No SDK, no API wrappers. First-party tools, no middleman.
What it doesn't do:
- No built-in editor (I use neovim btw)
- No built-in Git (use yours)
- No agent protocol/wrapper (run them directly in the terminal)
~1800 lines of TypeScript, ~0.3 MB installed. MIT licensed.
Landing page: https://jmux.build