LOCAL-FIRST PERSONAL AGENT online

TAKE CONTROL. KEEP IT LOCAL.

HALEN is your on-device writing partner for macOS.
No cloud. No upload. Just you, your data, your rules.

Download for macOS View on GitHub

$ brew install --cask halen

100% On-Device AI Your data never leaves your Mac.

Works Everywhere Assists in any app, any text field.

Built for Focus Lightweight, native, always out of the way.

RUNS LOCALLY

Halen runs on your Mac using local Gemma 4 models. No cloud, no data sharing.

[ 01 ]

WORKS IN ANY
TEXT FIELD

From Notes to Xcode, Halen assists right at the caret in any native macOS text field.

[ 02 ]

PRIVATE BY
DEFAULT

Your data stays on your device. You're in full control.

[ 03 ]

PLUGIN-READY

Extend Halen with powerful plugins and tailor it to your workflow.

[ 04 ]

LIVE DEMO

Watch Gemma 4 read your tone — without sending a byte.

The classifier runs in-process. The text never leaves the device. The output below is generated live in your browser, but mirrors the exact prompt path the macOS app uses.

01 text.pause → window 800 chars around caret
02 SHA-256 fingerprint → dedupe approved hashes
03 gemma4:e4b → tone label, ~120ms on M-series
04 Match against enabled rules → popover

~ halen / sentiment-guard.swift live

› // draft being typed in TextEdit

▍

› // gemma4:e4b classify(tone)

→ …

ASSIST AT THE CARET

One menubar app. Every plugin local. Toggle what you want, ignore the rest.

Tap any plugin to manage rules, snippets, or hotkeys. Nothing leaves the device. The toggles below are real — flip them.

4 of 4 plugins active · all on-device

Halen · macOS menubar

Halen menubar dropdown showing Typo Fixer, Sentiment Guard, Voice Dictation and Snippet Expander toggled on, with the Halen mascot in the background.

BUILT FOR YOUR WORKFLOW

Six surfaces, one local model.

Writing Help

Generate, refine, and iterate.

Auto-Fix

Typos, grammar, and punctuation on the fly.

Tone Awareness

Match tone and style to your audience.

Across Apps

Works wherever you type on macOS.

Zero Cloud

No uploads. No surprises.

0ms

Median tone classify on M-series

Bytes sent to a cloud, ever

0×

Plugins ship in the box

Open source, MIT-licensed

BUILT ON-DEVICE. BUILT FOR YOU.

HALEN is the personal writing agent you can trust — private by default, powerful by design, and always ready to help.

Learn more about HALEN →