What 'Allow Full Access' Means for iPhone Keyboards (and When to Turn It On)

Install a third-party keyboard on iPhone and, sooner or later, you'll meet a switch called Allow Full Access. Tap it and iOS shows a warning that the keyboard's developer could transmit what you type. That sounds alarming, and it's meant to make you stop and think.

So what does the switch actually do? Here's a precise explanation of how iOS handles custom keyboards, what Full Access permits, what it doesn't, and how to decide whether to turn it on.

The short version

Without Full Access, a third-party keyboard runs in a strict sandbox. It can't use the network or share data with its companion app, so it has no way to send what you type off your phone.
With Full Access, it can use the network and a few other capabilities, which is what features like AI rewriting or cloud sync require.
Full Access never lets a keyboard type into password fields. iOS swaps in the system keyboard there regardless.
It's a permission, not a behaviour. What a keyboard actually sends depends on the developer, so check what they say they do with it.

How iOS sandboxes keyboards by default

A custom keyboard on iPhone is an app extension: a small piece of an app that iOS runs separately from the app itself. By default, Apple keeps keyboard extensions on a very short leash. Without Full Access, a keyboard has no network access and can't share a data container with its companion app.

That doesn't mean a keyboard sees nothing. To work at all, it needs to know what you type with it, plus a limited window of text around the cursor in the current field. That's how autocorrect and deleting work. The sandbox simply ensures that, without Full Access, this text has nowhere to go.

Developers have to ask for Full Access explicitly in their keyboard's configuration. The switch only appears for keyboards that request it, which is why some keyboards in your list don't show it at all.

What turning on Full Access allows

Apple's documentation for custom keyboards (where Full Access is called "open access") lists the capabilities it unlocks. The main ones:

Network access. The keyboard can send text to a server for processing. This is the big one, and the reason for the warning.
A shared container with its companion app. Settings, custom dictionaries and preferences you set in the app can flow to the keyboard.
iCloud. For example, to keep settings or custom words in sync across your devices.
Access to other system services, such as Location Services or Contacts. These still require their own permission prompts. Full Access doesn't grant them silently.

Full Access applies to the whole keyboard. There isn't a per-app or per-field version: it's on everywhere you use that keyboard, or off everywhere.

The warning iOS shows is honest about the worst case. A keyboard with Full Access could transmit anything you type with it, which might include sensitive things like addresses or card numbers. It doesn't mean the keyboard will. It means you're trusting the developer not to.

What Full Access does not do

This is where a lot of confusion comes from. Turning on Full Access does not:

Unlock secure fields. In password fields and other secure text entry, iOS replaces any custom keyboard with the system keyboard. Custom keyboards also aren't used for phone-number pads.
Override apps that say no. An app can refuse third-party keyboards altogether. Some banking and security apps do, and Full Access makes no difference there.
Let the keyboard read your screen. A keyboard can't see other apps' content, other text fields, or what you typed with a different keyboard. It works with what you type through it and the limited context around the cursor.
Grant other permissions automatically. Contacts, Location and similar services still ask you separately.
Last forever. You can turn it off at any time. The keyboard loses network access, though basic typing usually keeps working.

When it makes sense to turn it on

Turn it on when a feature you actually want needs a server. Common examples: AI rewriting, syncing settings across devices, searching the web or GIFs from the keyboard.

Leave it off when you only want a different layout, a theme, or features that work offline. If a keyboard insists on Full Access for basic typing, that's worth questioning.

Before you flip the switch, it's reasonable to ask the developer (or read their privacy policy) for answers to these questions:

What is sent? Everything you type, or only text you explicitly submit?
When is it sent? Continuously, or only when you tap a specific button?
Who processes it? The developer's own servers, or a third-party service?
Is it stored? And if so, for how long?
What works without it? A good keyboard should still type without Full Access.

How to check which keyboards have Full Access

It takes about thirty seconds. Labels can shift slightly between iOS versions, but the path has been stable for years:

Open Settings and go to General, then Keyboard, then Keyboards.
You'll see every keyboard you've installed. Third-party ones are listed by app name.
Tap a third-party keyboard. If it requests Full Access, you'll see the Allow Full Access switch and whether it's on.
To remove a keyboard entirely, tap Edit on the Keyboards screen, or swipe left on it.

Many keyboard apps also show the same switches under their own entry in Settings, in a section called Keyboards.

How Rewritr uses Full Access

Rewritr is our iPhone keyboard for correcting, polishing and shortening text. Here is exactly how it uses this permission.

What stays on your iPhone. Typing, autocomplete and next-word suggestions run on the device. They use the system dictionary, built-in phrase ranking and a word history stored on your phone. They don't use the network and don't need Full Access.

What goes over the network, and when. Only explicit rewrites. When you tap the sparkle button and choose Correct, Polish, Shorten or a custom instruction, Rewritr sends the text you selected (or the paragraph around your cursor), the instruction, and your rewrite preferences to an AI model, Google Gemini. Nothing is sent while you're simply typing.

What happens without Full Access. The keyboard still works for typing and suggestions. If you tap a rewrite, Rewritr tells you to enable Full Access in keyboard settings instead. The Rewritr app also shows whether Full Access is on, marked as required for AI requests.

Because rewrites are processed by Google, we recommend not rewriting text you wouldn't want to send to an online AI service, such as card numbers or private medical details. Password fields are protected anyway, since iOS never lets a custom keyboard into them.

If you want to see the rewriting side in action, our guide on how to rewrite text on iPhone without switching apps walks through it.

Decide with the facts

"Allow Full Access" isn't a trap, and it isn't harmless either. It's a permission that lets a keyboard reach the internet, and its value depends entirely on what the developer does with it. Turn it on for keyboards whose features need it and whose explanations you trust, and check your list now and then. If you'd like a keyboard that only sends text when you ask it to, take a look at Rewritr.