Introduction

• bunmicro is a Bun JavaScript rewrite of the micro editor originally in Golang
• This project is not affiliated with Bun / Micro
• .
• Original project:
• https://github.com/micro-editor/micro
• .
• Mostly written by Claude or Codex
• But also some handwritten code

Unique features

Load URLs directly

• bunmicro url
• or inside the editor Ctrl-E open url

Long line protection

• In the original micro, if you open a minified file like vue.min.js it will be very slow due to re-highlighting
• In this Bun version, if line > 300 characters, re-highlighting is paused until ESC is pressed

Text-To-Speech

• Ctrl-E tts: Start reading from the current position
• Ctrl-E ttsspeed 2
• Ctrl-E ttspitch 1.1

Easy selection

• Mouse click on line numbers to select a range of lines
• Alt-s to enter selection mode
• Useful without a mouse on Android
• Also available: Ctrl-E act SelectRight

js plugin / command

• Instead of writing Lua, use your familiar JavaScript to extend functionalities
• runtime/jsplugins/name/name.js
• a full documentation in example.js
• an example plugin named chapter for turning to the next/prev page by number.
• It registers 2 commands: next/prevchapter
• js and eval js command explained at the bottom

Output highlighted text to terminal

• Works like bat ccat glow
• bunmicro -bat file
• aliases: --cat --bat --ccat --glow

Binary edit by hex3

• Edit binary files like text files
• bunmicro libc.so.6
• Ctrl+E reopen hex3
• Printable chars stay readable
  • a => a..
• Non-printable chars become escapes
  • \xff => \ff
• Search & Edit by plain text
• And simply save by Ctrl+S

Preview color schemes(theme)

• Ctrl-E theme, then press Tab and use arrow keys to preview

Mouse clicks more useful

• Almost every component on the screen is clickable or double clickable
• A complete help is at the end

Auto-completions arrow keys

• Press Tab and use up/down keys to select auto-complete items

action/js commands

• A complete help is at the end

Portability

• One codebase. One folder.
• Runs on Windows, Android, Linux
• No per-platform builds
• No native bindings
• No recompilation
• Just Copy folder -> Run with Bun

Version shows backends

• bunmicro --version shows http/clipboard/tts backends

Installation and basic usage

Option 1: Use npm

1. Install npm

• Android(Termux): pkg i npm
  • As of 2026/06/01
  • npm is the only way for automatically installing Bun for Android(Termux)
  • bunx is broken on Android
• Windows: .msi, macOS: .pkg
  • https://nodejs.org
• Linux: one of
  • sudo apt install npm
  • sudo apk add npm
  • sudo pacman -S npm
  • or use whatever package manager your OS provides

2. Install bunmicro

# Install Bun
npm install -g bun

# Run bunmicro(stable)
npx bunmicro
# npx bunmicro@latest to upgrade to new version

# npx bunmicro [options] [file1] [file2] ...
# alternative: bun bunmicro/src/index.js [options] [file1] [file2] ...
# if npx is not available, use npm x -- bunmicro

# Run bunmicro(shorter command, less stable)
# npm install -g bunmicro
# bunmicro

Option 2: Use Bun

• Android(Termux): Use npm
• You can install Bun at:
• https://bun.com

bun x bunmicro
# bun x bunmicro@latest to upgrade to new version

# bun x bunmicro [options] [file1] [file2] ... 
# alternative: bun bunmicro/src/index.js [options] [file1] [file2] ...

# If bunx is broken, follow the 2 steps below
# bun i -g --backend=copyfile bunmicro
# bun ~/.bun/bin/bunmicro

Basic features

• Inherited from the original Golang micro
• Only features listed here are implemented
  • There may be some differences from the original micro. Let me know if it's an obvious bug.
  • Send me an email directly:
  • [email protected]
• .
• Easy to use: No mode switching. Just start typing.
• Familiar key bindings (Ctrl-s=Save, Ctrl-c=Copy, etc)
• Panes(Splits) & Tabs (multitasking)
• nano-like key bindings menu by Alt-g or mouse click
• Extremely good mouse support
• Cross-platform: Copy the same bunmicro folder and run anywhere with Bun present
• Plugin system
  • From the original micro: written in Lua
  • From bunmicro: jsplugins in Bun JavaScript
  • runtime/plugins runtime/jsplugins
• diff gutter: diff color shown at the line numbers column
• autocompletion by pressing Tab
• Auto linting on save or command(lint) if tools are installed
• Syntax highlighting for over 130 languages
• Color scheme support (theme)
• Copy and paste with the system clipboard
• Small and simple (around 3MB)
• Common editor features such as undo/redo, line numbers, Unicode support, soft wrapping, etc

Useful key bindings:

• For a detailed help:

• Ctrl+E > help defaultkeys

• Ctrl-Q: Close current tab/pane, quits if it is the last tab/pane; prompts if modified

• Alt-q: Close current tab/pane, quits if it is the last tab/pane; prompts if modified

• Ctrl-S: Save

• Ctrl-O: Open

• Ctrl-G: Toggle help pane

• Ctrl-E: Command prompt

• Ctrl-K: Cut current line to detected clipboard backend

• Ctrl-F: Find

• Ctrl-Z: Undo

• Ctrl-Y: Redo

• Ctrl-A: Select All

• Ctrl-B: Shell prompt

• Ctrl-D: Duplicate Line/Selection

• Ctrl-T: Open a new tab

• Alt-g: Toggle nano-like key bindings menu

• Alt-h: replace [-l] text1 text2

• Alt-c: Toggle comment

• Alt-s: Selection mode

• Alt-, / Alt-p: Previous tab

• Alt-. / Alt-t: Next tab

• Alt-k / Alt-j: Move lines Up/Down

• Tab: Triggers autocomplete

• Esc: close command/shell prompt or terminal pane, rehighlight long lines

Mouse click actions

• Top Tabs:
  • Click: switch tabs
  • Double click: show complete file path
• Line numbers(gutter):
  • Click: select lines
  • Double click: toggle comment
  • also click on linter symbols to show the problem
• Filename: Switch tabs or show complete file path
• (row,col)
  • row to goto line
  • col to jump cursor between paired ()[]{} or Home/End
• Multi-window icon: new tab
• File type: switch highlighting languages
• Euro: Command prompt
• Unix/dos: toggle newline chars LF/CRLF
• Dollar: Shell prompt
• Encoding: Reopen with a specific encoding.
  • Show supported encodings by bunmicro --version
• Alt-G: Show nano-like key bindings menu
• Command/Shell Prompt row:
  • See the next section

Command/Shell Prompts

Command

• Internal commands for automating / tuning bunmicro
• Press Tab for available commands, arrow keys for selection
• In this Bun version, I added more commands like
  • act/action to do automation actions.
  • Press tab after act to get a list of them
  • or use help actions to show the list

eval — run code in py/js/sh

• Executed in a separate processs
• eval js — run selected text as JavaScript (via Bun)
• eval py — run selected text as Python (python3 / python on Windows)
• eval sh — run selected text as shell script (/bin/sh, or Bun shell on Windows)
• If no text is selected, append code inline:
  • eval js console.log("hi")
  • eval py print("hi")
  • eval sh echo hi
• Code after the language name is taken literally (no shell quoting)
• Output is shown in the terminal (same as Ctrl-B shell mode)
• Runs via a temp file (bunmicro-tmpXXXXXXXX.js/py/sh), deleted after execution

js — eval JavaScript inline

• Executed inside bunmicro's jsplugin context,
• js <expression or code>
• Code is passed raw to await eval (bypass shell quoting), result shown via alert
• Examples:
• js new Date().toISOString()
• js let ln=micro.getLine(); ln
• Implemented in runtime/jsplugins/example/example.js as a demo of micro.MakeCommand

Shell

• Executes a given shell command like sh -c
• Outputs the result to the original terminal before entering bunmicro

Prompt mouse gestures

• Click anywhere: move cursor to that position
• Click > or $ label: toggle between Command and Shell mode (input is preserved)
• Double click left ⅓ of row: newer history (same as ↓ key)
• Double click middle ⅓ of row: older history (same as ↑ key)
• Double click right ⅓ of row: execute the current input (same as Enter)

Prompt keyboard shortcuts

• Ctrl-U: delete everything before cursor
• Ctrl-K: delete everything after cursor
• Ctrl-A / Home: move cursor to start
• Ctrl-E / End: move cursor to end
• ↑ / ↓: navigate command history