mantis

An instant terminal code browser.

Linux / macOS:

curl -fsSL https://raw.githubusercontent.com/ansromanov/mantis/main/install.sh | sh

Windows (PowerShell):

irm https://raw.githubusercontent.com/ansromanov/mantis/main/install.ps1 | iex

mantis is a fast, lightweight tree viewer for reading code in your terminal: syntax highlighting, fuzzy search, and code folding in one small binary. No config required, with an optional plugin system when you want more. Built with ratatui.

mantis      # open the current directory and start browsing

That's it — no setup step. Press F1 for help (or ?), Ctrl+c to quit.

Why mantis?

mantis does one job: move through a codebase and read it, fast. It opens in milliseconds, needs zero config, and stays out of your way. It is not an editor — when you want to change something, press Ctrl+e to jump into your $EDITOR.

	mantis	Vim / Neovim	VS Code	Zed	Sublime Text
Interface	Terminal (TUI)	Terminal (TUI)	GUI (Electron)	GUI (native/GPU)	GUI (native)
Footprint	Single ~MB binary	Light core	Hundreds of MB + RAM	Native app (tens of MB)	Native app (tens of MB)
Setup to be useful	Zero — just run mantis	Hours of config & plugins	Install + extensions + indexing	Minimal	Minimal
Starts in	Milliseconds	Fast (slower with a big config)	Seconds	Fast	Fast
Fuzzy + full-text search	Built in	Plugins (fzf/telescope)	Built in	Built in	Built in
Syntax highlighting	Built in	Built in	Built in	Built in	Built in
Price	Free / OSS	Free / OSS	Free	Free / OSS	Paid (free eval)

mantis is the only row that's a read-only viewer — that's the whole pitch. Where the editors edit, mantis just gets you in, around, and back out fast, in any terminal.

What mantis is not

Be clear about the trade-offs before you install:

• Not an editor. No insert mode, no buffers, no saving — it reads, it doesn't write. Editing means handing the file to $EDITOR.
• No LSP / IntelliSense. No autocomplete, go-to-definition, diagnostics, or refactoring. It highlights syntax; it doesn't understand your code.
• No integrated terminal, debugger, or task runner. It's a viewer, not an IDE.
• Batteries are opt-in. Anything beyond the core (icons, extra languages, custom overlays) comes from plugins you enable yourself — less out-of-the-box than VS Code.
• Terminal-bound. A TUI in your terminal, not a GUI; icons need a Nerd Font.

If you want a fast, throwaway way to explore a repo, read a file, or skim a project without launching a heavyweight editor, that's exactly the gap mantis fills.

Features

Navigation

• Tree navigation by keyboard or mouse, respecting .gitignore
• Breadcrumb path bar; change root, go up a directory, double-click to descend
• Code folding (Space) — collapse/expand blocks, with language-aware fold regions

Search

• Fuzzy file-name search (Ctrl+T) — fzf-style, as you type
• Full-text content search (Ctrl+F) across the tree
• In-file search (/) and go-to-line (Ctrl+G)

Viewing & rendering

• Syntax highlighting for a wide range of languages
• JSON pretty-printing for minified files
• Word wrap, line numbers, and a status bar (line, language, scroll, encoding)

Productivity

• Command palette (Ctrl+P) — fuzzy-find every action with its keybinding
• Recent files (Ctrl+O), copy path
• Open in your $EDITOR (Ctrl+e) and drop back into mantis when you're done
• Auto-reload on disk change; session persistence (expanded dirs, open file, scroll) restored on restart, cached outside the repo

Customization

• Live theme switching — built-in presets, fully recolorable
• Remappable keybindings and configurable layout via a simple TOML file
• Nerd Font file-type icons (optional), full mouse support
• Opt-in plugins — extra languages, icons, markdown rendering, and custom overlays

Install

The one-liners above (no Rust toolchain required) download the prebuilt binary for your platform, verify its checksum, and install it onto your PATH. On macOS or Linux you can also use Homebrew:

brew tap ansromanov/mantis https://github.com/ansromanov/mantis
brew install mantis

From source:

git clone https://github.com/ansromanov/mantis.git
cd mantis && cargo build --release   # binary at target/release/mantis

See the installation docs for prebuilt binaries, Windows, and checksum verification.

Usage

mantis                          # view the current directory
mantis path/to/dir              # view a specific directory
mantis file.md                  # open a file directly
mantis --completions bash       # generate bash completions
mantis --print-man-page         # print the man page (mantis.1)
mantis --language rust < file   # highlight piped stdin as rust
mantis --update                 # self-update to the latest release

Press F1 for in-app help (or ?), and Ctrl+c to quit. For the full keybinding list and every action name, see the Usage & Keybindings guide — or press Ctrl+P in-app to fuzzy-find any action with its binding.

Shell completions for bash, zsh, fish, and PowerShell are generated automatically by the install script and Homebrew formula. Alternatively:

mantis --completions bash > /etc/bash_completion.d/mantis
mantis --completions zsh > /usr/local/share/zsh/site-functions/_mantis
man mantis    # view the man page

Plugins

mantis works fully without plugins, but a plugin system is there when you want to extend it. Two kinds:

• Process plugins — standalone executables that hook into app events and send actions back over newline-delimited JSON on stdin/stdout. They can add language providers (syntax highlighting + per-file-type fold regions), file-tree icons, custom overlays, and more. A plugin can be any executable — a compiled binary, a script, anything that reads stdin and writes stdout.
• Syntax plugins — .sublime-syntax files loaded into the highlighter at startup to add new file types without rebuilding mantis.

Press p for the plugin palette to enable/disable plugins; the choice persists across restarts (under [plugins] in mantis.toml). Bundled plugins auto-register and install on first enable, and a git-backed registry (index.json) lets mantis discover and fetch community plugins.

See the Plugins guide, Plugin Registry, and Plugin Development docs for the full protocol and manifest (plugin.toml) format.

Documentation

• Usage & Keybindings — every key and action
• Configuration — mantis.toml options and [keys]
• Themes — presets and every recolorable role
• Plugins — enable, install, and build plugins

See example.md for a document that exercises the markdown plugin's renderer (enable it with p in-app, or [plugins.markdown] in mantis.toml).

Development

just build     # debug build
just run .     # run against the current directory
just test      # run the test suite
just clippy    # lint

Contributing

Contributions are welcome! See CONTRIBUTING.md for how to build, test, and submit a pull request, plus the branch/commit conventions and what CI checks. Project conventions in depth live in AGENTS.md.

License

GPL-3.0-or-later © Andrei Romanov