How Arca writes in your voice and style

Arca writes in your voice by drafting from the same material you would use yourself: the thread it is replying to, what it remembers about you and the people involved, your past meetings, and the documents you keep. It matches the language and tone of the conversation, and it signs as you. You approve or redirect the draft before it goes out.

People often ask whether that means Arca "clones" you. It doesn't, and this post explains why that's not the goal. It also explains what Arca does today, so you can judge for yourself.

What "your voice" actually means

When someone says an email doesn't sound like them, they rarely mean the vocabulary. They mean things like:

• Language and register. You write to one client in formal Korean and to another in casual English. You'd never mix the two.
• Length and structure. Some people answer in two lines. Others always send a one-page summary up front.
• What you include. Your rate card, the two projects this client liked, the latest version of the document, not last year's.
• What you promise. You don't commit to a date you haven't checked. You don't say "attached" if nothing is attached.
• How you sign off. Small, but everyone notices when it's wrong.

Most of these are about context, not style. A generic AI draft sounds generic because the model doesn't know any of it. So the job is less about imitating your prose and more about giving the model what you know.

Where Arca gets it from

The thread itself

When Arca drafts a reply to an email or a Slack message, it writes in the sender's language and matches the tone of the conversation. A formal email gets a complete, polite email body with a greeting, the answer and a sign-off in your name. A quick Slack ping gets a quick reply.

Memory

As you use Arca, it extracts durable facts from your conversations and meetings: who people are, your preferences, the projects you're running, the commitments you made. It skips anything transient or already known. When Arca drafts, it can draw on that memory instead of starting from nothing. You can see it as a map in the app, sorted into what it knows about you, your preferences, projects, facts, insights and meetings.

Your meetings

Arca records meetings on your Mac without a bot joining, separates speakers, and writes the summary, decisions and action items. That record is what lets a follow-up email say what was actually agreed, not a vague "great chatting today."

Your documents

Arca keeps a document vault. When someone asks for a document that's in the vault, such as a business registration or a certificate, Arca picks the exact file, mentions it in the draft, and attaches it. If several files match, it chooses the most recent and relevant one.

How you correct it

No assistant gets your voice right on the first day. What matters is how cheap it is to fix.

Every reply draft in Arca comes with a one-line question, like "Reply with the latest registration attached?" You can approve it, skip it, or type a direction instead. Directions are plain language:

• "That's the old one, use the January version."
• "Politely say I'll send it next week."
• "Shorter."

Arca rewrites the draft to match, and re-picks the attachment if needed. If your direction says not to reply at all, it drops the draft. If it couldn't apply the direction, it keeps what you typed instead of silently throwing it away.

Style is also about craft

"Your voice and style" isn't only about emails. On our homepage there is a side-by-side: the same brief given to the same model, once directly through ChatGPT and once through Arca. The first comes out as a crowded stock-style layout. The second is an editorial two-page spread with a clear headline and restrained type. That comparison is a product demonstration, not a benchmark. But it shows what we care about: the gap between "the model can do it" and "this looks like something I'd send."

Decks, documents, websites and content are part of what Arca makes. For those, taste is the whole job. The same instruction can produce slop or something you're proud of, depending on the context, the references and the care that goes into the request.

We also route each task to the model that suits it, rather than sending everything to the most expensive one. That's how we keep good work affordable enough to use every day.

What Arca deliberately won't do

There is a version of "writes like you" that we decided against.

It won't post as you in secret. Our product spec rules out silent "second self" posting. When Arca handles a message on its own, it should be because you allowed that level of autonomy, the item is low-risk, and the reply discloses that Arca helped.

It won't promise what it can't deliver. If a draft says a document is attached but Arca can't find the file, that draft is never sent automatically.

It won't send sensitive replies without you. Anything involving money, negotiation, commitments or judgment is treated as non-routine. You get the draft and the decision.

It won't treat incoming text as instructions. The messages Arca reads are written by other people. If one of them says "mark this routine" or "attach the contract," Arca ignores it and judges only what the sender is legitimately asking for.

Sounding like you is worth very little if it comes with the risk of saying something you'd never say. We'd rather Arca ask one more question than send one wrong email.

Where this is going

Today, Arca's sense of your voice comes mostly from context: the thread, your memory, your meetings and your documents. The more you use it and correct it, the more it has to work with. We're early, and there's a lot left to do. Arca is in early access on iPhone and Mac, and you can join the waitlist.

FAQ

Does Arca copy my writing style?

Arca drafts from your context rather than imitating your prose: the thread it's replying to, what it remembers about you and the people involved, your meetings, and your documents. It matches the language and tone of the conversation and signs as you.

How do I fix a draft that doesn't sound like me?

Approve it, skip it, or type a direction in plain language, such as "shorter" or "politely say I'll send it next week." Arca rewrites the draft, and re-picks the attachment if needed.

Will Arca send messages as me without telling me?

No. You choose Arca's autonomy level, sensitive topics always come to you, and Arca's product spec rules out silent posting as you. When Arca handles a low-risk message on its own, the reply should disclose that Arca helped.

What does Arca use to learn about me?

Durable facts it extracts from your conversations and meetings: who people are, your preferences, your projects and your commitments. It skips anything transient, and you can see what it knows in the app.

Can Arca make documents and decks, not just emails?

Yes. Decks, documents, websites and content are part of what Arca makes, in your voice and style. The examples on heyarca.app are product demonstrations.