Email autocomplete for your Mac

What email autocomplete looks like mid-sentence

You start the thought. Nextline predicts the continuation from the words already in the field — not from a prompt, and not from your mailbox. In each line below, the grey half is the suggestion.

• Apple Mail · reply to a client

  Thanks for the detailed notes — I’ll go through them Nextline suggests: this afternoon and send you a revised draft by Thursday.

• Outlook · declining a meeting

  I won’t be able to make Tuesday, but I’m Nextline suggests: free any time Wednesday afternoon if that works for you.

• Gmail in your browser · following up

  Circling back on last month’s invoice — let me know if Nextline suggests: you need anything else from us to get it processed.

• Apple Mail · status update

  Quick update on the migration: staging is done and we’re Nextline suggests: planning to move production over on Friday evening.

Tab takes the next word or the whole line. Keep typing to ignore it; the suggestion updates around what you actually wrote. Each suggestion is generated from the sentence in front of it, so nothing is being pasted back from a stored block of text you wrote earlier.

How it works

1. 01

   Install and allow access

   Install Nextline, then grant its macOS Accessibility permission. Nextline sits in the menu bar; there’s no Mail plug-in, browser extension, or mailbox connection.

2. 02

   Write your email as usual

   When a text field has focus, Nextline reads the text around your cursor and puts the rest of the line ahead of it in grey. A local language model produces that prediction on your Mac.

3. 03

   Press Tab

   Take the next word, or the whole line. Nothing is inserted unless you accept it, and nothing is ever sent on your behalf.

That interaction is the same in every supported Mac app. Because the model runs locally, suggestions continue with no network.

Not an inbox assistant, and not a draft generator

Some AI-powered email assistants read the inbox, prioritize messages, and draft replies. Nextline does none of that.

If you want an inbox agent, choose a product built for that job. Our Gmail Smart Compose alternatives guide compares prompt-based drafting, replacement inboxes, and inline completion.

Inline continuation, full-draft AI, and saved snippets

These three tools are often grouped together, but they solve different problems. Some people use more than one because they act at different moments.

The split that matters is known text versus unknown text. A disclaimer, a mailing address, or the same onboarding answer for the ninth time is snippet work, and a predictor is the wrong tool for it — the Nextline and TextExpander comparison works through that in detail. A message you’re composing for the first and only time has nothing to expand, which is where a continuation earns its place. And if you write almost entirely inside one Gmail tab, Google’s own suggestions may already be enough; Nextline versus Gmail Smart Compose says so plainly.

Where you can autocomplete email today

Nextline works in the text field that has your cursor, so the mail apps below are supported through the same system-wide integration; no mail-specific plug-in is required.

App	Status
Apple Mail	Supported
Gmail (web)	Supported
Outlook	Supported

Gmail runs in a browser, so that row depends on which one you use: Safari, Chrome, and Firefox are listed as supported, while Arc and Dia need one setup step before suggestions appear inline. Elsewhere on your Mac the same continuation follows you into Slack, Messages, Teams, Notion, Word, Pages, and Apple Notes — though not everywhere, and Google Docs is one of the apps we can’t reach yet. Statuses change as apps and Nextline both ship, so treat the live compatibility list as the source of truth and check it before you rely on a specific app.

What happens to what you write

Email often contains sensitive work and personal information, so the data flow is worth stating precisely.

• Your writing stays on your Mac. The model that produces suggestions runs on your machine. There’s no server-side text processing, which is also why suggestions work offline.
• Nextline reads only the field you’re in. It sees the text around your cursor through the macOS accessibility APIs, holds it in memory just long enough to produce the suggestion, and doesn’t write your typing to disk.
• No Nextline account. There’s no sign-up or mailbox connection. Your writing stays on your Mac; optional product analytics use a pseudonymous installation ID and never include your text.
• Password fields are off limits. macOS marks secure fields as protected and doesn’t expose them to accessibility apps, so Nextline can’t read or suggest into them.
• You hold the switch. Nextline works only with the Accessibility permission you grant, and revoking it in System Settings, or quitting the app, stops all reading immediately.

The app does use the network for three things — update checks, the one-time model download, and pseudonymous product analytics you can switch off — and none of those requests can carry your text. The privacy policy spells out each one, including what the analytics do and don’t contain.

Limitations, and when to pick something else

A short list of things Nextline won’t do for your email, so you can rule it out quickly if one of them is what you came for.

• It won’t write the message for you. No prompts, no full drafts, no “reply to this thread”. If that’s the job, Google’s Help me write and the dedicated assistants in our alternatives guide are built for it and Nextline isn’t in the running.
• It won’t give you the same paragraph back. Suggestions are generated fresh every time, so there’s no exact recall. Boilerplate belongs in a text expander — see the TextExpander comparison, which also covers the free options.
• It doesn’t fix what you already wrote. Nextline predicts ahead of the cursor; it doesn’t correct grammar, tone, or spelling behind it today. A proofreader is a different tool for now.
• It doesn’t mine your sent mail. Nextline has no inbox access, so it cannot build a profile from mail you have already sent. Gmail offers personalized Smart Compose suggestions inside Gmail; if you write only there, it may be the better fit.
• It doesn’t reach every app. Some apps do not expose their text through the macOS accessibility APIs, so Nextline cannot find the cursor there. The compatibility list names the exceptions.
• It’s macOS only, on Apple Silicon. An Apple Silicon Mac running macOS 14 or later, with no Windows, iPhone, or iPad version — so it has nothing to offer in a mail app on your phone. There’s no published list of supported languages either.

Questions