Disclosure: I build DraftKey, one of the tools below. I've tried to describe every option, mine included, as plainly as I can.
Lots of Mac writing tools now call themselves "private," and the word covers very different things. Some send every keystroke to a server under a privacy policy. Some run a model on your Mac but still call out for harder requests. Some never send your text anywhere.
If you write client emails, legal drafts, health notes or code comments you don't want stored on someone else's server, that difference matters. Here's how the main options compare in October 2026.
What "on-device" should mean
When I evaluate a tool, I ask four questions:
- Where does inference run? On your Mac's GPU or Neural Engine, or on a server?
- Is there a cloud fallback? Some tools quietly hand harder requests to a remote model.
- What still needs the internet? Model downloads, license checks and updates are normal. Sending your text is a different thing.
- Can you turn it off per app? You probably don't want any assistant reading your password manager or your terminal.
Almost every system-wide Mac writing tool works through macOS Accessibility, which lets it read the text field you're typing in. That's how they work across apps, and it's also why you should trust whoever made the one you install.
The cloud option: Grammarly
Grammarly is still the default for many people. The Mac app works across desktop apps and browsers, and its grammar and tone suggestions are mature.
It is cloud-based: text is sent to Grammarly's servers for analysis, and it needs an internet connection. You can turn it off per app, and it tries to skip sensitive fields such as passwords. There's a free plan, and Grammarly Pro is listed at $12/month billed annually or $30 month-to-month.
Good for: polished grammar and tone suggestions when cloud processing is acceptable.
Not for: anything you're not allowed to send to a third party.
The built-in option: Apple Intelligence Writing Tools
On Apple silicon Macs with Apple Intelligence turned on, Writing Tools can proofread, rewrite, change tone and summarize text in most apps, for free.
Apple's privacy page says basic requests run on-device, but more complex requests can go to Private Cloud Compute. That's Apple's server setup, which Apple says only processes the data needed for the request, doesn't store it, and can't be accessed by Apple. You can review those requests in System Settings → Privacy & Security → Apple Intelligence Report. macOS also has its own inline predictive text for short completions.
Good for: free, good-enough rewrites with a strong privacy design.
Caveat: "mostly on-device" isn't the same as "always on-device." It's a request-based tool, so you select text and pick an action. It's not continuous AI autocomplete.
Third-party apps that run on-device
All of these need an Apple Silicon Mac, and most need macOS 14 or later.
Cotypist is AI autocomplete that predicts your next words in any Mac app, running on your Mac. It offers the most personalization of any app here: learning your voice, per-app instructions, and screen- and clipboard-aware suggestions on higher tiers. There's a free tier (100 accepted completions a day) and a 30-day Pro trial. After that, Plus is $72/year for one Mac and Pro is $108/year for up to three.
Shadowtype is free and open source. It runs GGUF models through llama.cpp and Metal, showing next-word suggestions in light gray text (ghost text) plus rewrites of selected text with ⌥⌘K: improve, shorten, make formal or casual, fix grammar, summarize. You can bring your own model, and it runs a local OpenAI-compatible endpoint and an MCP bridge, which developers will like. The trade-off is that you manage more yourself.
Refine is an offline grammar checker built on a local Gemma model. It checks as you type, explains each fix, and supports many languages, with a floating editor for rewrites and translation. Its site lists it as free with no account. Note that it optionally lets you plug in your own API key for cloud models. That's off by default, but if you enable it, those requests leave your Mac.
TypeTab is focused on autocomplete. Predictions run on the Apple Neural Engine, and it says no account and no telemetry. It's free to try, then $49 one-time.
DraftKey is my app. It does on-device autocomplete plus instruction-based rewriting: tap ⌘ and ⌥ together in a text field, choose an action or type a request like "make it shorter," review the result, then insert it. It works on the current paragraph or your selection. It also has optional mechanical keyboard sounds and a local clipboard history, each with its own toggle. The writing model is a separate ~1.12 GB download, and AI features need 8 GB of memory. After setup the model works offline. The internet is only used for the model download, license activation and update checks. There are per-app controls, and secure fields are excluded. It's a $5 lifetime license for up to three Macs.
Weak spots: it's a young app, the model is small so it won't match a large cloud model on complex rewrites, and some custom editors don't expose their text to Accessibility, so it can't work there.
Comparison
| Tool | Where text is processed | Autocomplete | Rewriting | Price | Requirements |
|---|---|---|---|---|---|
| Grammarly | Cloud | Suggestions | Yes | Free plan; Pro $12/mo annual or $30/mo | Internet required |
| Apple Writing Tools | On-device, complex requests may use Private Cloud Compute | No (macOS has basic predictive text) | Yes | Free | Apple silicon, Apple Intelligence |
| Cotypist | On-device | Yes | Word alternatives | Free tier; $72–$108/yr | macOS 14+, Apple Silicon |
| Shadowtype | On-device | Yes | Yes | Free, open source | macOS 14+, Apple Silicon |
| Refine | On-device (optional bring-your-own-key cloud) | No (grammar checks) | Yes | Free | macOS 14+ |
| TypeTab | On-device | Yes | No | $49 one-time | macOS 14+, Apple Silicon |
| DraftKey | On-device | Yes | Yes | $5 lifetime (up to 3 Macs) | macOS 14+, Apple Silicon, 8 GB RAM |
How I'd choose
- Your text may never leave the machine (client work, NDAs, regulated data): rule out Grammarly, and remember that Apple's Writing Tools can use Private Cloud Compute. Pick one of the on-device apps and check its network activity yourself with Little Snitch or LuLu.
- You mainly want grammar fixes: Refine, or Apple's Writing Tools if PCC is fine for you.
- You mainly want autocomplete: Cotypist if you want deep personalization and don't mind a subscription, TypeTab for a one-time purchase, Shadowtype for free and open source.
- You want autocomplete and rewriting in one small paid app: DraftKey or Shadowtype. Shadowtype is free and more hackable. DraftKey is more of a ready-to-use app.
A note on testing claims
Don't take "100% private" on trust, mine included. Install the tool, turn on a network monitor, type a paragraph, and watch what connects. An on-device assistant should be quiet while you write, apart from the license and update checks it tells you about. Ten minutes of testing tells you more than any marketing page.
Which one are you using, and did it pass the network-monitor test?
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