A keyboard sees everything you type, which makes it the one place an AI writing assistant can help in every app at once: Messages, Mail, Slack, WhatsApp. On iPhone, four paid keyboards are worth a serious look if you write a lot for work. They do surprisingly different jobs. Grammarly corrects and polishes, QuillBot paraphrases, Wordtune offers other ways to say the same thing, and Tonely tells you how a message is likely to feel to the person reading it.

Free keyboards such as Gboard, SwiftKey and Apple’s own are fine for typing. This guide is about the subscriptions: what each one adds for the money, how well it handles tone, and where the text you type is sent to be analyzed. That last question matters more for a keyboard than for almost any other app.

The four keyboards at a glance

Prices as listed in each app’s in-app purchases on the US App Store on October 13, 2026. All four list a free tier, but watch for free trials that turn into a paid subscription unless you cancel; see Grammarly below. This guide compares the paid plans.

1. Grammarly: the all-rounder, if you’re happy to use the cloud

Grammarly’s keyboard is the most complete of the four. It checks spelling, grammar and conciseness as you type, predicts words, swipes, and in recent versions adds voice dictation that cleans up filler words. A tone detector tells you how a message comes across, and the paid plan, Grammarly Pro (still called Premium in the App Store), adds tone rewrites plus clarity and vocabulary suggestions. A tap rewrites the whole message shorter, more fluent or in a different tone.

What sets it apart is the explanation. Tap a suggestion and Grammarly says why it’s there, which makes it as much a teacher as an editor. It also works on iPad, and the same subscription covers Grammarly on the Mac and in the browser.

Grammarly has a free plan, but the iPhone app steers new users toward a free trial of Pro, and the trial turns into a paid subscription unless you cancel it at least 24 hours before it ends. If you only want the free version, decline the trial, or cancel it in Settings › your name › Subscriptions right after it starts; you keep the trial until it runs out.

The bigger trade-off is privacy. Grammarly’s checks run on its servers, so the keyboard needs Full Access and an internet connection before it will check anything, tone included. Without Full Access it is just a keyboard. Grammarly offers an opt-out from using your text for product improvement in its trust center; it’s worth setting before you type anything sensitive. At $139.99 a year it is also the most expensive of the four, though the mobile-only plan brings that down to $83.99.

• What we like: the widest feature set; explanations that teach; tone detection on the free plan; works on iPhone and iPad and across your other devices.
• What to know: nothing works beyond typing until you grant Full Access, and then your text is checked on Grammarly’s servers; the app pushes a trial that renews as a paid plan; tone rewrites and the more useful suggestions need Pro; the full plan is the priciest here.

Who it suits: people who want one subscription to make all their writing correct and polished, on every device, and who are comfortable with a cloud service reading it.

2. QuillBot: for when you need to say it differently

QuillBot grew up as a paraphrasing tool, and that is still the heart of its keyboard. Select a sentence and it rewrites it in one of several modes, two of them free and eight with Premium, to change the tone, the formality or the length. The keyboard also fixes grammar, translates between more than 40 languages, and can draft text from a prompt. The app around it adds an AI detector, a “humanizer” and an AI chat.

It is a strong choice for reshaping text you already have, less so for judging tone: it gives you new versions rather than telling you what was wrong with the old one. You need a QuillBot account, and the company says it can use inputs to improve and train its own models, with opt-outs that are documented for its browser extension. Check them before relying on it for anything confidential.

• What we like: the most flexible paraphrasing; translation built in; $99.99 a year, less than Wordtune or Grammarly’s full plan.
• What to know: account required; your text is processed by QuillBot’s service and may be used for training unless you opt out; tone is something it changes rather than something it explains.

Who it suits: students and writers who often need to reword, shorten or translate, and who want it in the keyboard instead of a separate app.

3. Wordtune: better alternatives, one sentence at a time

Wordtune, from AI21 Labs, does one thing particularly well: it shows you several alternative ways to phrase what you wrote, from a single word to a whole sentence, and lets you push them more casual, more formal, shorter or longer. It can also generate text from a prompt, including through Siri, and rewrite into English from another language, which many non-native speakers find useful.

Seeing three alternatives side by side is a good way to notice how much a word choice changes the feel of a message. The catch is that it is a rewriter, not a reviewer: it won’t warn you that a message sounds abrupt, you have to ask. Its privacy policy covers the content you submit, including for service improvement and research, so read the policy if that matters to you. The iPhone app was last updated in May 2026, less often than the others here.

• What we like: excellent alternative phrasings; easy control over tone and length; rewriting from other languages into English.
• What to know: no automatic tone warnings; text is processed on Wordtune’s service; updated less often than the other three.

Who it suits: people who know what they want to say but want a better way to say it, especially in a second language.

4. Tonely: tone feedback that leaves the words to you

Tonely is the odd one out, and the closest to what many people actually want from a tone checker. It doesn’t correct or rewrite. It reads your message and tells you how it might feel to the other person: encouraging, controlling, passive-aggressive, supportive. You can pick the voice its feedback comes in, from formal and professional to warm, direct or casual. It works as a keyboard and as an iMessage extension, so you can also use it without switching keyboards.

Tonely says its analysis runs entirely on your iPhone, that it can’t read or store your messages and that it doesn’t train on them (privacy policy). You still create an account for the membership. It is also the newest and smallest product here, so expect fewer features and a shorter track record. The tone feedback itself needs the paid membership.

• What we like: made for tone rather than grammar; feedback instead of rewrites; on-device analysis; the lowest monthly price of the four.
• What to know: tone feedback is members-only; no grammar or rewriting tools; a new app from a small company; you need an account.

Who it suits: anyone whose real worry is “how will this land?”, especially in personal or sensitive conversations, and who prefers their text to stay on the phone.

Privacy: where does your text go?

A keyboard is the most privileged app on your phone, so it’s worth understanding one setting: Full Access. Without it, iOS keeps a third-party keyboard offline, so whatever it does has to happen on the device. With it, the keyboard can reach the internet, and that is how most AI keyboards work: your text is sent to a server, analyzed, and the result sent back. Granting Full Access doesn’t mean a keyboard misuses your text, but it does mean you’re trusting that company with everything you type in it. Apple explains what Full Access allows.

• Cloud: Grammarly, QuillBot and Wordtune analyze your text on their servers. Each has a privacy policy and, in Grammarly’s and QuillBot’s case, a training opt-out worth finding.
• On the device: Tonely says its tone analysis runs locally. You can check what any keyboard can do in Settings › General › Keyboard › Keyboards, where Full Access is shown per keyboard.

iOS always switches back to its own keyboard for password fields, whichever one you use.

So which one?

Start from the problem you actually have, not the longest feature list:

1. “I want my writing correct and polished everywhere.” Grammarly. Nothing else here covers as much, and the explanations will improve your writing over time.
2. “I keep needing to reword things.” QuillBot for heavy rewording and translation, Wordtune if you prefer picking from a few well-made alternatives.
3. “I worry about how my messages come across.” Tonely. It is the only one of the four built mainly around tone, and the only one that keeps the analysis on the phone.

Whichever you try, watch the first screens: these apps often start with a free trial that renews as a paid subscription. A week of real use will tell you more than any comparison, and afterwards check Settings › your name › Subscriptions for anything you didn’t mean to keep.

Where RiskCheck fits

We’re building RiskCheck, a tone-checking keyboard for iPhone, so we have an obvious interest here and have left it out of the ranking: it isn’t on the App Store yet. Like Tonely, it leads with feedback. Four signals above the keys show whether a message reads as risky, heated, unprofessional or unclear. The difference that matters most is privacy: every check runs on the iPhone and RiskCheck works fully without Full Access, so iOS itself can keep it offline and nothing you type can leave the phone. Its word predictions come from its own on-device language model too. It can also suggest a calmer rewrite, written on the iPhone by Apple’s on-device model, which makes it more limited than the cloud rewriters above and is why it shows the rewrite next to your message rather than replacing it. We’ll add it to this comparison once it’s available and has been tested the same way.

Questions people ask

What is the best AI keyboard for iPhone?

For most people who write for work, Grammarly, because it does the most: grammar, tone detection, rewrites and dictation on iPhone and iPad. If tone is your main concern, Tonely is the more focused choice. For rewording, QuillBot or Wordtune.

Is the Grammarly keyboard safe to use?

Grammarly is an established company with a public trust center and a training opt-out. But its keyboard won’t check anything, tone included, until you grant Full Access, and from then on what you type with it is sent to Grammarly’s servers. Whether that is “safe” depends on what you type. Switch to another keyboard for anything you wouldn’t forward to a third party: health, legal, HR or financial messages.

Grammarly vs QuillBot vs Wordtune: which is better?

They overlap less than it seems. Grammarly is best at correcting and polishing, QuillBot at paraphrasing and translating, and Wordtune at offering a few better-phrased alternatives. If you can only pay for one and write mostly at work, Grammarly covers the most ground.

Is Grammarly Premium (Pro) worth it on iPhone?

If you write a lot of email and messages on your phone, the mobile-only plan at $83.99 a year is the better deal. The full plan at $139.99 a year makes sense only if you also use Grammarly on a computer. Either way, the app usually starts you on a free trial that renews automatically, so cancel in time if you decide against it.

Do AI keyboards need Full Access?

Any keyboard whose AI runs on a server does, because iOS won’t let a keyboard reach the internet without it. Grammarly, QuillBot and Wordtune are in that group. A keyboard that does its AI on the device doesn’t have to, and can still work with Full Access turned off.

Is there a keyboard that checks tone without sending my text to a server?

Tonely says its tone analysis runs on the device. RiskCheck, which we’re building, runs entirely on the device and works fully with Full Access turned off, so iOS can keep it offline.

RiskCheck is our product, which is why it isn’t ranked. We haven’t been paid by any of the companies above, and we’ve tried to be fair to each, including where they do more than we do. Prices and features are as listed by each company on October 13, 2026.

Written by Boris Vidolov, Founder/CEO of Escaped Intelligence.