YOUR AI WRITING ASSISTANT BEHIND ONE HOTKEY

Let AI write anything,
in your voice.

Press J in any app, sketch what you mean, and send a polished message that still sounds like you. Never generic, never off-tone.

FREE IN BETA · MACOS 13+ · ON-DEVICE OPTION
TRUSTED BY PEOPLE WHO WRITE ALL DAY AT
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J
# Replying to Mara in #design-team
Type a rough idea…
esc dismiss
The loop
Summon with ⌘J
Sketch a rough idea
It writes in your voice
Send without leaving

Fragments are fine. CMD + J gathers the context around the thread, who's talking and what was just said, and uses it to turn three words into a finished message you'd actually send.

Built for people
who reply fast for a living.

CMD + J accelerates founders, sales, customer succes, engineers and product manager

Sounds like you

It learns from messages you've already sent, then matches your tone: warm, concise, lightly playful, whatever you actually are.

Thanks for flagging. I'll take a look this afternoon and follow up.
Tone matched warm · concise

Knows the context

It gathers the context around your reply: who you're talking to, what was just said, which channel. It uses that so every draft fits the conversation, not a blank page.

# Replying to Mara in #design-team
Reading the thread…

Everywhere you type

Slack, Mail, Teams, any text field. One system-wide hotkey, the same result.

Private by default

On-device option. Context is read in the moment and never stored.

You're in control

Review and edit every draft before it sends. It never sends on its own.

Under two seconds

Sketch the gist, hit enter, done. A finished draft before you'd finish typing.

One hotkey,
every kind of message.

Slack replies, emails, Teams pings, even a clean AI prompt. Pick the format and CMD + J shapes the draft to fit it.

You type looks great, ship friday, one note on permissions
Replying to Mara in #design-team
Just went through it, looks great. Happy to ship Friday. One small note on the permissions step before we do.
Tone matched work · concise
You type ask procurement for an updated quote, 12 seats, need it wed, call possible
To Procurement · Re: License renewal
Hi team, could you send an updated quote for 12 seats on our current plan? We'd like to finalize the renewal by next Wednesday. Happy to hop on a quick call if that's easier.
Tone matched formal · warm
You type deploy slipping to monday, qa found an edge case, timeline update monday
Posting in General · Engineering
Quick heads-up: the deploy is slipping to Monday. QA caught an edge case in the permissions flow and we'd rather fix it properly than rush it out today. I'll share an updated timeline first thing Monday.
Tone matched direct · calm
You type write a blog post about our new onboarding, make it good
Prompt for Claude · ChatGPT
You're an experienced product marketer. Write a 600-word post announcing our redesigned onboarding for existing customers. Tone: clear and upbeat, no hype. Cover what changed, why it's faster, and one short customer-style example. End with a single call to action to try it.
Shaped into a clean prompt structured

Start free.
Upgrade when it sticks.

Free

$0 / forever

The core ⌘J HUD system-wide · up to 3 connected apps · on-device voice training.

Download now

Pro

$8 / month

Unlimited apps · cloud voice training on full history · multiple tone profiles · priority models.

Download now

Your words
stay yours.

CMD + J reads a conversation only while you're actively replying to it, and you choose where the work happens. Nothing is sent without you.

On-device option

Run voice analysis locally so your messages never leave your Mac. Cloud is opt-in, never the default.

Nothing is stored

Context is read in the moment and discarded the second your draft is done. No transcripts, no archive.

You're in control

Review and edit every draft before it sends. CMD + J never sends a message on its own.

Let AI write your next message,
in your voice.