It’s not a cat, not a bat, but rat: your terminal’s new best friend. rat stands for Render All Text (at least, that is one way to read it): a lightweight CLI that turns Markdown and LaTeX into terminal-friendly Unicode text, with a Vim/Neovim plugin for live JSON-RPC rendering.

For best Unicode glyph rendering in terminals and editors, JuliaMono is recommended.

• Markdown to Unicode/plain-text output
• LaTeX to Unicode/plain-text output
• Works with files or stdin
• JSON-RPC mode for editor integrations
• Vim/Neovim live preview plugin included

macOS (Apple Silicon):

mkdir -p ~/.local/bin
curl -fL https://github.com/tani/rat/releases/download/nightly/rat-darwin-arm64 -o ~/.local/bin/rat
chmod +x ~/.local/bin/rat

Linux x64:

mkdir -p ~/.local/bin
curl -fL https://github.com/tani/rat/releases/download/nightly/rat-linux-x64 -o ~/.local/bin/rat
chmod +x ~/.local/bin/rat

If needed, add this to your shell profile:

export PATH="$HOME/.local/bin:$PATH"

Verify:

rat --help

Requirements: bun

git clone https://github.com/tani/rat.git
cd rat
bun install
bun run compile

Render Markdown from stdin:

echo "# Hello\n\n*world*" | rat

Render Markdown from a file:

rat examples/EXAMPLE.md

Render LaTeX from stdin:

echo 'Term: \(\alpha^2 + \beta\)' | rat --language=latex

Render LaTeX from a file:

rat --language=latex examples/EXAMPLE.tex

Language options:

• --language=markdown (default)
• --language=latex
• Also accepted: --language markdown / --language latex
• Backward compatibility: --latex

Install with vim-plug:

Plug 'tani/rat', { 'rtp': 'vim/' }

Commands:

• :RatOpen
• :RatClose
• :RatToggle

Behavior:

• Live preview updates on edit and cursor move (TextChanged, TextChangedI, CursorMoved, CursorMovedI)
• Cursor sync to preview (CursorMoved, CursorMovedI)
• Sends JSON-RPC params.language automatically:
  • latex for tex, plaintex, latex
  • markdown for everything else

Start server mode:

rat --json-rpc

Supported methods:

• render with params: { text, cursor?, language? }
• shutdown

Example request:

{"jsonrpc":"2.0","id":1,"method":"render","params":{"text":"A: $\\alpha+\\beta$","language":"latex"}}

Example response:

{"jsonrpc":"2.0","id":1,"result":{"text":"A: α+β","cursorMapping":{"sourceLine":1,"sourceColumn":1,"renderedLine":1,"renderedColumn":1,"strategy":"line-anchor","confidence":1}}}

previewLine and sourcemap were removed in favor of cursorMapping.

@rat/unicode-sourcemap now exposes a mapper object API:

import { createUnicodeSourcemap } from "@rat/unicode-sourcemap";

const mapper = createUnicodeSourcemap(sourceText, renderedText);
const offset = mapper.mapOffset(42);
const cursor = mapper.mapCursor({ line: 10, column: 1 });
const line = mapper.mapLine(10);
const lines = mapper.mapLines();

bun test
bun run test:vim
bun run lint
bun run typecheck
bun run format:check

MIT. See LICENSE.