Show HN: Ttmux, a Modern and Fast Tmux

Developer statico released ttmux, a terminal multiplexer written entirely with Anthropic's Claude Code, now available in beta via Homebrew or built from source with Rust 1.82 or later. ttmux ships with defaults tmux requires plugins for, including no escape-key delay, 10,000 lines of scrollback versus tmux's 2,000, mouse support, truecolor and undercurl, OSC 52 clipboard, kitty keyboard and modifyOtherKeys, and kitty/iTerm2/sixel image support, plus floating panes, a TOML config, a settings screen, and per-pane busy/needs-you/done agent marks. The project warns the config format will change before 1.0.

A modern multiplexer alternative. Warning Beta software. ttmux is still under test. Expect bugs, and expect the config format to change before 1.0. Note Made entirely with Claude Code https://claude.com/claude-code . Every line of this project was written by Claude. ttmux runs many terminals in one window, like tmux or screen. It adds floating panes, real mouse support, curved borders, and a settings screen that you open inside the app. With Homebrew, on macOS or Linux: brew install statico/tap/ttmux Or build it from source, which needs Rust 1.82 or later: cargo install --git https://github.com/statico/ttmux Then start it: ttmux Prebuilt binaries for macOS and Linux are also on the releases page https://github.com/statico/ttmux/releases . tmux works well and has decades of muscle memory behind it. But a fresh tmux needs a .tmux.conf and plugins like tmux-sensible https://github.com/tmux-plugins/tmux-sensible before it stops getting in the way. ttmux ships with those defaults. | | tmux, out of the box | ttmux | |---|---|---| | Escape key | a delay after esc 500ms before 3.5 | no delay, so vim leaves insert mode at once | | Scrollback | 2,000 lines | 10,000 lines | | Mouse | off | on: click, drag, resize, and wheel | | Color | truecolor and undercurl need terminal-overrides | truecolor and undercurl | | Focus events | off | on | | Clipboard | ignores OSC 52 from programs | copies to your clipboard, or set clipboard = false | | Modern keys | extended-keys off, so shift+enter is lost | kitty keyboard and modifyOtherKeys | | Images | sixel if built in, the rest need allow-passthrough | kitty, iTerm2, and sixel, even mpv video, and nothing but images | | Config | .tmux.conf , source-file by hand | TOML, reload with the prefix and r , or a settings screen | | Discovering keys | a list behind the prefix and ? | a which-key popup and a command palette | | Layout | tiling | tiling or free-floating, drag and drop | | Agents | — | a per-pane busy, needs-you, or done mark | On first start ttmux asks which keymap you want: Modern, tmux, or screen. Change it later in settings or with general.keys-preset , and rebind any key under keys . Keys for each keymap | Action | Modern ctrl+t | tmux ctrl+b | screen ctrl+a | |---|---|---|---| | Split right | v or % | % | \| | | Split down | s | " | S | | Move the focus | h j k l | arrows | tab | | Resize the pane | H J K L | | | | Zoom the pane | z or o | z | | | Float one pane | f | | | | Next layout | space | space | | | New, next, previous tab | c n p | c n p | c n p | | Last tab | ctrl+t | | | | Move the tab left or right | < | | | | Break the pane into a tab | | | | | Join the pane into a tab | @ | | | | Rename the tab, the pane | A , a | , , . | A , . | | Scroll back, or copy mode | or esc | | esc | | Paste what copy mode copied | | | | | Close the pane | x or q | x | K | | Close the tab | & | & | | | Command line | : | : | : | | Command palette | ; | | | | Send the prefix | t | ctrl+b | a | | Settings | , | | | | Help | ? | ? | ? | | Detach | d | d | d | | Quit ttmux | Q | | | Every keymap also has these, with no prefix: | Key | Action | |---|---| | alt+arrows | Move the focus | | alt+shift+arrows | Resize the pane | | ctrl+alt+right / down | Split right or down | | ctrl+alt+w | Close the pane | | ctrl+alt+f | Switch between tiling and free mode | | ctrl+alt+z | Zoom the pane | | ctrl+alt+t | New tab | | ctrl+alt+p | Command palette | | ctrl+alt+, | Settings | | ctrl+alt+n | Go to the next pane that wants you | | shift+pageup / pagedown | Scroll back and forward | Press the prefix and ? in the app for the full list. tmux's copy mode is off by default, because programs like coding agents copy on their own and want the mouse drag. Set general.copy-mode = true and the scroll back key opens it: move with h j k l , press v to start a selection and y to copy it, or q to leave. A mouse drag over a pane also copies. The copy goes to your clipboard and to a paste buffer that the prefix and types back. Hold the prefix and a popup lists what can follow it, like which-key in neovim. Turn it off with general.which-key = false . The prefix and : open a command line for the scripting commands below. Tab completes a command or a flag, and the row above shows the usage of the command you are typing. A name you type is yours. A program can set a title with an escape sequence, but that title never replaces a name you set, and it names the pane, not the tab. The tab takes the title only while it holds one pane. Every text field takes the readline keys, including ctrl+a , ctrl+e , ctrl+w , ctrl+k , ctrl+u , ctrl+y , alt+b , and alt+f . Lists move with ctrl+n and ctrl+p , and ctrl+g cancels. ctrl+alt+f turns the grid of panes into a window manager. Drag a title bar to move a pane. Drag any corner to resize it. Click to raise it. Tiling mode gets the same mouse support for dividers. Grab the line between two panes and drag it. ttmux works like tmux. The server keeps your panes alive after you detach. ttmux attach to the default session, or start it ttmux new -d -s work start a session in the background ttmux attach -t work attach to a named session ttmux ls list the sessions ttmux kill-session -t work stop one ttmux upgrade move a session to a server started from here ctrl+t d detaches. ttmux upgrade moves a live session to a new server. The shells, jobs, and screens stay. Add -t work for a named session. Use it for two things: - A new version. Install the new build, then run ttmux upgrade . The session then runs on the new build. - The macOS keychain and permission prompts. macOS ties them to the terminal that started the server. When that terminal quits, panes cannot unlock the keychain or show a permission prompt. To correct this, run ttmux upgrade in a terminal window that is not inside ttmux. ttmux doctor tells you if a session has this problem. The scrollback comes back as plain text, and inline images are lost. When a client attaches, new panes get its SSH AUTH SOCK , DISPLAY , and the other variables in general.update-environment . If the client does not have one of them, new panes do not get it either. Every pane can drive the session it lives in. The commands are tmux's, so a tmux script mostly runs unchanged. The commands ttmux send-keys -t %2 "make test" Enter type into a pane ttmux split-window -h split side by side, prints %2 ttmux capture-pane -t %2 -S - read a pane, scrollback and all ttmux new-window open a tab, prints its number ttmux select-pane -t %2 or -L -R -U -D ttmux list-panes %2: 80x24 zsh active ttmux list-windows 1:build 2 panes active ttmux rename-window build name a window ttmux display-message "done" show text in the status bar ttmux join-pane -s %3 -t 2 move a pane into window 2 ttmux break-pane and back out into its own ttmux run toggle-zoom any key-binding action A target is a pane id from list-panes , or a window number counted from 1. With no target the command acts on the pane it was run from, or the focused pane outside ttmux. The session is the one $TTMUX SESSION names, which every pane already has set. ttmux --help prints the full list. API.md https://github.com/statico/ttmux/blob/main/API.md is the full reference: every command, every flag, the exit codes, and recipes. ttmux <command --help prints one command, and ttmux list-commands --json prints the whole API for an agent to read. The file is ~/.config/ttmux/ttmux.toml . ttmux writes it for you on the first save. Every key in it is also in the settings screen, so the file is for version control and the screen is for changes. After you edit the file, press the prefix and r to reload it. ttmux does not reload it on its own, because widget commands in it run as you, and a program that writes the file should not get them run unasked. An example config general mouse = true scrollback = 10000 free-mode = false keys-preset = "vim" vim | tmux | screen passthrough-images = true kitty, iTerm2, and sixel inline images clipboard = true programs may copy with OSC 52 notifications = true programs may send OSC 9, 99, and 777 copy-mode = false tmux's copy mode and mouse-drag copy update-environment = "SSH AUTH SOCK", "DISPLAY" taken from each client that attaches appearance border-style = "curved" curved | square | heavy | double | dashed | divider | none border-focused = " 7aa2f7" gap = 0 status.footer enabled = true left = "session", "mode" center = "tabs" right = "agents", "time" agents enabled = true bell-on-attention = true Overrides on top of the preset. "none" unbinds a key. keys "ctrl+t v" = "split right" "ctrl+t &" = "none" A widget runs a shell command and shows what it prints. Give it a name under status.widgets , then put that name in a row. How widgets work status.footer enabled = true right = "disk", "time" status.widgets.disk command = "df -h / | awk 'NR==2 {print $5}'" interval = 60 seconds between runs, 0 runs it once The command runs with sh -c , so pipes, globs and ~ work. ttmux uses the first line of the output. tmux markup such as fg=red,bold is honored, so a script written for tmux status-right works without a change. A slow command does not block the screen. It runs in its own thread, and ttmux does not start a second copy while the first one runs. A pane that runs a coding agent gets a mark: ◐ for busy, ● for wants you, and ✓ for done. The status bar counts the panes that wait on you, and ctrl+alt+n goes to the next one. The patterns live under agents , so this works with any agent. ttmux is built against Ghostty and iTerm2. Any terminal with 24-bit color and SGR mouse reporting works, including Alacritty, kitty, WezTerm, and Terminal.app. Ghostty and alt+arrows Ghostty never sends alt+left and alt+right to ttmux, because it binds them to the word motions of readline. To get horizontal focus movement back, unbind them in the config of Ghostty: keybind = alt+left=unbind keybind = alt+right=unbind What programs inside a pane can count on: - Truecolor, and undercurl, dotted, dashed and double underlines in color - Emoji with skin tones, flags and ZWJ sequences as one wide cell - Kitty keyboard protocol and modifyOtherKeys, so shift+enter works - Kitty, iTerm2 and sixel images, including mpv --vo=kitty video - Synchronized output, so redraws do not tear - Focus events, and a cursor shape per pane - OSC 52 copy to your clipboard, and OSC 9, 99 and 777 notifications, each of which can be turned off - Answers to cursor position, device attributes, window size, mode, color and XTGETTCAP queries, so fzf, neovim and fish do not stall - Dark or light theme reports CSI ?996n , mode 2031 - Scrollback that keeps output scrolled under a fixed footer, as Claude Code and Codex draw, and CSI 3J to clear it - Pastes that cannot close their own bracket early - No accidental nesting: attaching from inside a pane is refused, as in tmux macOS on Apple silicon and Intel, and Linux on x86 64 and aarch64. CI builds and tests all three. SECURITY.md https://github.com/statico/ttmux/blob/main/SECURITY.md describes the threat model, the hardening, how ttmux compares with tmux, and how to report a vulnerability. make check format, lint, and test, the same as CI make help all the targets MIT licensed.