Disclosure: Nextline publishes this guide and is one of the tools in the category it describes. Every claim about a named product links to that vendor’s own page. Prices and availability change — follow the links before deciding anything.

An AI typing assistant is software that reduces the number of keystrokes between what you mean and what ends up in the text field. That is the only definition broad enough to be true, which is also the problem: five different mechanisms are sold under the phrase, and they are not substitutes for one another. Predictive text completion finishes a sentence you started. Grammar correction fixes what you already wrote. Text expansion inserts text you saved earlier. Full-draft generation writes the whole message from an instruction. Assistive word prediction is a different field again, built for people whose access to a keyboard is the constraint.

Search for predictive text AI, typing AI, or AI typing and results from all five arrive mixed together. This guide separates them so you can name the job first and pick the tool second.

The five kinds of AI typing assistant

Predictive completion

You type. The software proposes the rest of the phrase or sentence, usually in grey ahead of the cursor. You accept it with a key — often Tab — or keep typing straight through it and it re-predicts.

Gmail’s Smart Compose is the version most people have met. Google documents accepting a suggestion with Tab on a computer or a swipe on mobile, and lists support for English, Spanish, French, Italian, and Portuguese. Products in this category are sometimes marketed as sentence completion software, AI completion, or, on a desktop, AI autocomplete. The mechanism is the same: continuation of text that already exists in front of the cursor.

You still set the direction: start the sentence, inspect the suggestion, and accept or ignore it.

Grammar correction

This category looks backwards. A grammar and style checker reads what you have written, flags spelling, agreement, punctuation, and tone problems, and offers a replacement. Your Mac already does a basic version of this in most native text fields; dedicated checkers go further into style, clarity, and consistency.

Correction and prediction act at different moments, even when one product offers both. A checker works on existing text; a completion feature proposes what comes next. They can be used together because they serve different jobs.

Saved-snippet text expansion

A text expander watches for a trigger you defined earlier — ;addr, sig1 — and swaps it for a block of text you wrote in advance. There is no prediction involved. The value is exact repetition: a disclaimer, a mailing address, a refund policy, the paragraph legal approved.

TextExpander offers fill-in fields, nested snippets, scripting, and shared team libraries. Its Individual plan is $39.96 per year, with a 30-day trial and no free plan. Espanso is free, open source, and runs on macOS, Windows, and Linux. Your Mac also includes Text Replacement under System Settings, then Keyboard; replacements can sync to your iPhone and iPad through your Apple Account.

The rule of thumb is simple. If you know the exact words before you need them, this is the right category and prediction is the wrong one. We work through that split in more detail in the Nextline and TextExpander comparison.

Full-draft generation

Here you supply an instruction — “decline politely and suggest next Thursday” — and the tool returns a complete draft or rewrite. Gmail’s Help me write, the general-purpose chat assistants, and the drafting panels bolted onto email clients all work this way.

This is the largest change to how you write, because the software makes decisions about content, structure, and tone that you then review and edit. Google’s Help me write is also the clearest example of availability being conditional: Google’s current page restricts it to eligible Workspace or Google AI plans, with supported personal accounts limited to the United States.

Full-draft tools are a poor fit for short replies, where describing the message takes longer than writing it, and a good fit for the long message you have been avoiding since Tuesday.

Accessibility and assistive word prediction

Assistive word prediction software serves a different context. AAC software, literacy-support tools, and on-screen keyboards can reduce the physical or cognitive cost of producing text for people using switches, eye gaze, a single finger, or phonetic spelling. These systems may also include speech output, scanning, abbreviation expansion, and specialist vocabulary.

We are not going to rank products here, because the fit depends on an individual assessment that a blog post cannot perform. What is worth stating is the boundary: a mainstream typing assistant that predicts text is not the same thing as validated assistive technology, and should not be treated as a substitute for it. Nextline included. Nextline reads the text around your cursor through the macOS accessibility APIs — the same system that powers VoiceOver — but that is a technical integration, not an accessibility claim. It has not been evaluated as assistive technology, and we make no claims about accessibility outcomes.

Compare the five at a glance

Category What it acts on You start with Typical output Main job
Predictive completion The sentence in front of your cursor A few words you typed An inline continuation you accept or ignore Type less of what you were already writing
Grammar correction Text you already wrote A finished draft or sentence A flagged span and a suggested fix Catch errors and tighten style
Saved-snippet expansion A trigger you defined An abbreviation The exact stored text, character for character Reproduce known wording reliably
Full-draft generation An instruction or a thread A prompt A complete draft or rewrite Decide and express the whole message
Assistive word prediction Each partial word or phrase Keystrokes, switches, or gaze Ranked word candidates, often with speech Lower the physical or cognitive cost of producing text

The same sentence through each tool

One scenario, five behaviours. You are replying to a client about a delayed rollout, and you have typed: “Thanks for flagging this — the Q3 rollout”.

  • Predictive completion offers “is now scheduled for the week of the 12th” in grey. You glance at it, decide it is right, press Tab. If it is wrong you keep typing and it disappears.
  • Grammar correction does nothing yet. Once you finish the paragraph it may flag a comma splice or tell you “we are currently in the process of reviewing” is padded.
  • Snippet expansion does nothing either, unless you type your trigger — after which the entire standard delay-notification paragraph appears exactly as you saved it last quarter.
  • Full-draft generation is not in this flow at all. You would have opened a prompt box first and asked for “a short apology for the Q3 delay with a new date”, then edited what came back.
  • Assistive word prediction would have been working from the first letter, offering rollout, review, revised after r and speaking the options aloud if configured to.

Notice that the first, third, and fifth all reduce keystrokes, and none of them do it in a way the others could replace.

Where text prediction already exists

Before buying predictive text software, check what is already on the machine — a lot of text prediction ships free.

Phone keyboards have offered next-word suggestions for over a decade, which is where most people’s intuition about prediction comes from. That intuition undersells current tools, which complete phrases and sentences rather than single words.

Browsers and web forms autofill saved values — names, addresses, card details — and some now surface writing suggestions inside text areas. This is form autofill rather than language prediction, and it is a common source of the “why am I still seeing suggestions after I turned that off?” confusion.

Email clients may have their own layer, like Smart Compose in Gmail, which is separate from the keyboard and separate from anything installed system-wide.

Education settings require a policy check. A school may allow prediction as an accommodation in one context and prohibit it where independent writing is being assessed; rules vary by institution and task.

If several of these run at once, they can look like one feature misbehaving. Turn off one source at a time to find out which control is responsible.

Limitations worth knowing first

  • A plausible continuation can still be wrong. Google warns explicitly that Smart Compose is not designed to provide answers and may not always predict factually correct information. That caution applies to the whole category. Names, dates, numbers, and commitments need reading before you send.
  • Prediction cannot fix what is behind the cursor. If you want proofreading, buy a proofreader. Nextline, for one, predicts what comes next and does not correct spelling or grammar today.
  • Snippets and prediction are not interchangeable. No amount of AI predictive text will reproduce approved wording character for character, and no snippet library helps with the sentence you are writing for the first and only time.
  • Coverage is never total. Desktop tools depend on what each app exposes. Nextline cannot reach apps that do not expose their text through the macOS accessibility APIs, which is why it publishes a live compatibility list.
  • Where the text goes varies enormously. Some tools process on the device, some send text to a server, some connect to your mailbox. This is the question to ask first if you write anything confidential; see our privacy policy for how Nextline answers it.
  • Tone needs close review. Predictive suggestions often favor conventional phrasing. For a delicate message, inspect each suggestion carefully; typing it yourself may be faster than correcting a poor fit.

If you want an AI typing assistant for Mac

Match the job to the category before you install anything.

If most of your writing is the same text over and over, get a text expander — TextExpander, Espanso, or the Text Replacement panel already in System Settings. If you want whole emails written from an instruction, get a full-draft tool, and check that your account is eligible before assuming it is included. If you want errors caught, get a checker. In all three cases a completion tool is the wrong category.

What is left is the case for predictive completion: most of what you write is different every time, you already know roughly what you want to say, and the cost is in typing it out. Nextline is a Mac app for that job.

It places a grey continuation ahead of your cursor in supported Mac apps, including Mail, Outlook, Slack, Messages, Notion, Word, and Pages. Its model runs locally, so your writing is not sent to us and suggestions continue offline.

Nextline requires an Apple Silicon Mac running macOS 14 or later and is free during early access.

It is also not a text expander, not a grammar checker, not an email client, and not an assistive technology product. If you want to see how it lines up against the closest named alternatives, read the Gmail Smart Compose comparison or the guide to email autocomplete on a Mac. If it sounds like the right category, download it for Mac — after checking your apps are on the list.

Frequently asked questions

What is the difference between a typing assistant and autocomplete?

Autocomplete is one kind of typing-assistant feature: it predicts what comes next. “Typing assistant” is the broader term and may also include grammar correction, snippets, or full-draft generation.

Is text completion the same as text prediction?

They are used interchangeably, with a slight difference in scale. “Prediction” often implies the next word, as on a phone keyboard; “completion” usually implies the rest of the phrase or sentence. Both describe guessing forward from what you have typed.

Does an AI typing assistant learn how I write?

Some do, and the mechanism matters more than the claim. Gmail offers a Smart Compose personalization setting that tailors suggestions to your usual writing. Nextline adapts on the device and lets you add your own terms — a client name, internal jargon — that it then becomes likelier to predict. A tool that learns your style by uploading your writing to a server is making a different trade, and it should say so in its policy.

Can prediction software help with accessibility needs?

Word prediction is a long-established feature of assistive and AAC software, and for some people it is central to writing at all. But the right product depends on an individual assessment, usually with a specialist, and general-purpose typing assistants are not assessed or validated for that use. Do not substitute one for the other on the strength of a shared feature name.

Is a typing assistant allowed at school or work?

That depends on the institution and the task, not on the tool. Prediction that helps a slow typist finish notes may be unacceptable in a writing assessment, and workplaces with confidentiality rules often care about where the text is processed more than what the feature does. Check the policy before you install.

Do these tools work offline?

A tool can work offline only if everything needed for suggestions is on the device. Nextline does; many cloud assistants do not.

Which category should I choose if I only write short replies?

Predictive completion, most likely. Short replies are where prompt-based drafting is slowest — describing the message costs more than writing it — and where a snippet library only helps if the reply is genuinely identical each time.