How to fix grammar in any app on iPhone

Typos and grammar slips are easiest to fix before you hit send. The keyboard is the one thing every app on your iPhone shares, so a keyboard that checks your writing as you type catches mistakes in Messages, WhatsApp, Mail, Slack and everywhere else.

Set up GKeyboard (about a minute)

Install GKeyboard from the App Store and open it. It is free and there is nothing to sign up for.
Open Settings → General → Keyboard → Keyboards → Add New Keyboard and choose GKeyboard.
Tap GKeyboard in that list and turn on Allow Full Access. iOS asks this of every keyboard that connects to the internet, and GKeyboard needs it to fetch AI suggestions. Without it you still get the keyboard, autocorrect and word suggestions.
In any app, touch and hold the globe key below the letters and pick GKeyboard.

The app walks you through the same steps when you first open it.

Fix mistakes as you type

Type as you normally would. GKeyboard checks your text after a short pause, so it stays out of your way.
When it spots a spelling, grammar or punctuation mistake, the fix appears in the bar above the keys.
Tap the fix to accept it.
If there is more than one, tap the number to see every suggestion with a short explanation, then accept or dismiss each one.

Fix a whole message at once

Tap ✦ above the keys to open the AI panel and choose Fix grammar, or Improve for a cleaner version. You see the result before it goes into your message. The same panel has 9 one-tap styles, from Shorten to Formal and Friendly, for when the grammar is fine but the tone is not.

What it costs

Grammar checks are free, with a daily allowance that resets at midnight. GKeyboard Pro raises it to 1,000 checks a day for people who write a lot (A$2.99 a month or A$19.99 a year in Australia; the App Store shows your local price).

Good to know

Autocorrect and spell check work offline. Grammar suggestions need Full Access and an internet connection.
No suggestion bar showing? Check that GKeyboard is the active keyboard (hold the globe key) and that Allow Full Access is on.
In password and other private fields the AI is off on purpose, so you will see no suggestions there.

What happens to your text

There is no account: no name, email or phone number.
Autocorrect, word suggestions and spell check run on your iPhone.
With Full Access on, the text you are writing in the current field is sent over an encrypted connection to the GKeyboard server, which passes it to OpenAI to make the suggestion. That can be the whole message around your cursor, not just one sentence.
The GKeyboard server does not store that text and filters it out of its logs.
The AI switches off in password, email, URL, number, one-time code and credit card fields.
Turn off Full Access at any time and GKeyboard sends nothing; it keeps working as an on-device keyboard.

The privacy policy has the details.

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