Lekho (লেখো) — Avro Phonetic Bangla Keyboard for macOS

The only Avro Phonetic keyboard built natively for Apple Silicon Macs.

Lekho brings Avro Phonetic-style Bangla (Bengali) typing to Apple Silicon Macs natively (M1, M2, M3, M4, M5) — no Rosetta required. If you used Avro Keyboard on Windows, iAvro on macOS, or OpenBangla Keyboard on Linux, Lekho is your native Apple Silicon alternative.

Download | Website

Why Lekho?

The existing Bangla keyboard options for macOS each have limitations on Apple Silicon:

• Avro Keyboard (OmicronLab) — Windows-focused, no native macOS build
• iAvro — Intel-only macOS build that runs on Apple Silicon through Rosetta. Apple has announced Rosetta support is being wound down — fully available in macOS 27, then limited to legacy games starting in macOS 28. macOS already shows a deprecation warning on Intel-only input methods.
• OpenBangla Keyboard — Linux only (Qt-based), no macOS port
• macOS built-in Bengali — Apple's own layout, not Avro phonetic

Features

• Avro Phonetic typing — type ami banglay gan gai → আমি বাংলায় গান গাই
• 150k word dictionary with smart suggestions and autocorrect
• Smart emoji suggestions — type কান্না and get 😢, বাংলাদেশ and get 🇧🇩, right in the candidate panel
• Three typing modes — Phonetic-first (default: your exact spelling by default with the suggestion list still one keypress away), Smart (suggestions, autocorrect, and emoji pick the word for you), or Phonetic-only (pure character-by-character control, no popup). Switch anytime in Settings.
• Your font, your size — draw the suggestion popup in any installed Bangla font (July, Ekush, Noto Sans Bengali, …) at the size you like. Nothing bundled, so the app stays tiny.
• Native Apple Silicon — ~2.2 MB, instant startup, zero CPU when idle
• Works on all Apple Silicon Macs — MacBook Air, MacBook Pro, iMac, Mac Mini, Mac Studio (M1/M2/M3/M4/M5)
• Works everywhere — built with Apple's InputMethodKit framework
• Completely offline — no internet, no data collection, no telemetry
• Signed and notarized — signed with an Apple Developer ID and notarized by Apple, so it installs like any other Mac app, no security warnings
• Free and open source (MPL-2.0) — no ads, no subscription

Install

Option A — Download the DMG (recommended)

1. Download the latest .dmg from Releases
2. Open the DMG and double-click Install Lekho.pkg

To update later, download the new DMG and run the installer again. No log out needed.

Option B — Homebrew

brew install --cask arahim3/lekho/lekho

That single command auto-taps and installs Lekho. Then jump to step 3 below to add the input source.

To update later: brew upgrade --cask lekho. To uninstall: brew uninstall --cask lekho.

After brew upgrade, Lekho may disappear from the input menu. Homebrew removes the old app a few seconds before it installs the new one, and macOS takes Lekho off the menu in the meantime. To bring it back, open System Settings → Keyboard → Input Sources → Edit, remove Lekho with −, and add it again with +. Your settings and learned words are kept. Updating with the DMG installer doesn't cause this.

Final steps (both options)

1. Go to System Settings → Keyboard → Input Sources → Edit, click +, find Lekho, and add it

1. Use Globe key or Ctrl+Space to switch to Bangla

Typing modes

Open the Settings tab in the Lekho window to pick how typing behaves:

• Phonetic-first (default) — your exact phonetic spelling is committed by default, but the suggestion list is still one keypress away. Lekho remembers the words you deliberately pick.
• Smart suggestions — dictionary, autocorrect, and emoji pick the best-matching word when you press space.
• Phonetic-only — pure transliteration, no suggestion popup, autocorrect, or emoji.

Changes apply immediately — no restart needed.

Fonts

The Fonts tab lets you pick which installed Bangla font draws the suggestion popup, and how big. Only the popup changes — apps show the words you type in their own font. Only fonts installed on your Mac are listed; the tab links to a few good free ones (July, Ekush, Google's Noto Sans Bengali) and re-scans every time you open the list.

Requirements

• macOS 13 (Ventura) or later
• Apple Silicon Mac (M1/M2/M3/M4/M5)

Build from Source

Prerequisites: Rust toolchain, Xcode (for Swift and InputMethodKit).

# Install Rust (if not already)
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
rustup target add aarch64-apple-darwin
Build
make build
Install to ~/Library/Input Methods/
make install
Create distributable .dmg
bash scripts/create_dmg.sh

Local builds are ad-hoc signed and work fine on your own Mac. Official releases are signed with a Developer ID and notarized; the scripts only do that when those certificates are in your keychain.

Architecture

Swift (InputMethodKit)  ←→  Rust Engine (riti) via C FFI

• Rust engine (engine/) — wraps OpenBangla/riti, compiled as a static library
• Swift IMK layer (Lekho/) — subclasses IMKInputController, handles key events, candidate window, and text commits
• No Xcode project — built with swiftc + cargo + shell scripts

Contributing

Contributions are highly welcome! Whether it's reporting a bug, suggesting a feature, or submitting a pull request to improve the Swift or Rust codebases, feel free to get involved.

For anything bigger than a small bug fix, please open an issue before writing code — see CONTRIBUTING.md.

Credits

Lekho is powered by OpenBangla's riti engine — the same Bengali transliteration engine behind OpenBangla Keyboard on Linux.

Feedback

Found a bug or have a suggestion? Open an issue.

License

MPL-2.0

Keywords: Avro keyboard Mac, Bangla keyboard macOS, Bengali typing MacBook, Avro phonetic Apple Silicon, অভ্র কিবোর্ড ম্যাক, বাংলা টাইপিং ম্যাক

Maintained by Abdur Rahim