danterm

danterm is a fast macOS terminal built in Swift with no third-party dependencies.

Why?

I like vertical tabs, which for years meant using iTerm2 on macOS.

In the LLM era the terminal is becoming more and more central to my workflow, not less. So, I decided to build my own to satisfy my own preferences.

It runs on its own Swift terminal engine -- grid, parser, renderer, and pty, with no third-party dependencies. It started as an AppKit wrapper around libghostty, but LLMs made writing the engine itself tractable, and the project doubles as a testbed for automating high-quality software with AI.

Ideals

• Everything should be both keyboard- and mouse-driven
• The terminal engine should be reusable outside of danterm, embeddable by other projects
• Cross-platform

Features

• Vertical tabs
• Split panes that inherit the current working directory
• Persistent pane alerts and macOS notifications (click a notification to focus its pane)
• Local and remote color themes
• Save, restore, and crash-recover tabs, panes, and the commands running in them
• Semantic pane states ("idle", "running command (make test)", "running agent claude (busy)") reported by shell and agent integrations
• Full control via danterm command-line interface for scripts and coding agents
• Remote IPC over a Tailscale tailnet (docs)
• Config file
• Drive danterm running on macOS machine over Tailnet via iPhone app (Experimental)
• Linux GTK4 app (WIP)
• And much more

Performance

Measured on a MacBookPro18,1 running macOS 26.5.2. Every terminal ran at 170x60 in Menlo 13.

Throughput

kitten __benchmark__ --render, 3 reps, median MB/s as the kitten reported it.

The kitten times parsing, not rendering: terminals render asynchronously, and --render only stops them from being asked not to.

Memory

10 tabs, each running an inert sleep. Activity Monitor phys_footprint, sampled every second for 10 seconds after a 5 second settle, median reported. One rep, so read these as a rough ranking rather than a precise number.

The scrollback case writes 10000 full-width lines per tab. iTerm2 and kitty were capped at 10000 lines. danterm and Ghostty bound scrollback by bytes instead of lines: danterm at 16 MB per pane (it kept all 10004 rows), Ghostty at 10 MB per surface (retention not readable).

Install

Requires macOS 26 on Apple Silicon.

Download the latest .dmg from GitHub Releases, then move DanTerm to /Applications. Releases are Developer ID signed and notarized, and the whole app is an 8 MB download.

If your shell tools need them, grant DanTerm Full Disk Access and Developer Tools in System Settings under Privacy & Security.

Nix

DanTerm ships a flake and a Home Manager module: docs/integrations/nix.md.

Configure

Press Cmd+, to edit ~/.config/danterm/config.json, Cmd+Shift+, to reload it. Every setting has a default, so a new config file holds only {"schemaVersion": 1}.

Nix users can point this file at a dotfiles repository so app edits survive a rebuild: docs/integrations/nix.md.

Integrations

DanTerm is a plain terminal to everything you run in it. These are the tools it does something extra with, or that need a setting to work well with it.

A tool earns a page here when DanTerm ships code for it, or when DanTerm's behavior with it differs from a plain terminal's. Everything else just works and needs no page.

danterm doctor  # Check permissions, CLI, hooks, skills, jq, and configured font.

Shortcuts

The app menus list all shortcuts. Rebind them in Settings > Key Bindings or the config file: docs/keybindings.md.

Command-line interface

danterm ls
danterm tab new --cmd 'just test'
danterm pane split -h
danterm pane read --pane "$DANTERM_PANE" --lines 50

See integrations/danterm/SKILL.md for all commands and examples, and the terminal capability contract for terminal behavior.

Develop

bash ./dev-build.sh --no-install  # Build without replacing an installed app.
just provision-worktree           # Run once in a new Git worktree.
just launch-slot                  # Run an isolated development copy.
just test                         # Run the test suite.

License

MIT