Secure File Storage App for iPhone: How to Choose One

Short answer: The right secure file storage app depends on where you want the files. For files synced to the cloud, use end-to-end encrypted storage: iCloud Drive with Advanced Data Protection, Proton Drive, Tresorit, or Cryptomator on top of the cloud you already have. For files that stay on your iPhone behind their own code, use a vault app.

This guide is for anyone keeping IDs, contracts, tax papers or medical files on an iPhone. It starts with what iOS already gives you, then compares popular apps using facts from their App Store pages. Steps checked against Apple’s documentation for iOS 26 and later.

First, decide what “secure” means for you

People mean two different things by secure file storage, and no single app does both perfectly.

• Safe from the company storing the files. You want the cloud provider, a hacked server or a data request to see only scrambled data. That takes end-to-end encryption: files are encrypted on your iPhone before upload, and the keys stay on your devices.
• Safe from people who use your phone. You want a partner, child or friend who knows your iPhone passcode to be unable to open the files. That takes a separate code, which most built-in iOS locks don’t have.

Most people need some of both. Keep that in mind as you read the options.

Option 1: iCloud Drive with Advanced Data Protection (built in)

iCloud Drive is already on your iPhone and shows up in the Files app. With standard data protection, files are encrypted in transit and on Apple’s servers, but Apple holds the keys. That lets Apple help you recover your data, and it means Apple could read it.

Advanced Data Protection changes that. iCloud Drive becomes end-to-end encrypted, with the keys only on your trusted devices.

1. Open Settings and tap your name.
2. Tap iCloud, then Advanced Data Protection.
3. Tap Turn on Advanced Data Protection.
4. Set up a recovery contact or a recovery key when asked. Apple can’t recover your data for you after this.

Good for: files you want on all your Apple devices, without a new app or account. Limits: anyone who knows your iPhone passcode can open the Files app and read them. Files you share with “anyone with the link” are not end-to-end encrypted, even with Advanced Data Protection on.

Option 2: Lock the Files app and individual PDFs (built in)

You can touch and hold the Files icon and tap Require Face ID, so Files asks for Face ID before it opens. You can also lock a single PDF with its own password: open it in Files, tap the file name at the top, then tap Lock PDF.

These help against someone casually picking up your phone. Your iPhone passcode still opens a locked Files app, and a locked PDF is still listed by name. The full steps and their limits are in how to hide files on iPhone.

Option 3: An end-to-end encrypted cloud storage app

These apps work like Dropbox or Google Drive, but encrypt files on your iPhone before upload. You need an account with the provider.

Proton Drive comes with 5 GB of free storage, with paid plans for more. Its App Store page lists end-to-end encryption, share links with a password and expiry date, a PIN or biometric lock for the app, photo backup, offline access and version history. Its App Privacy label lists only diagnostics, not linked to you.

Tresorit describes itself as end-to-end encrypted file sync and sharing, with files encrypted on the device before upload, shared folders, two-factor authentication and an app passcode. The iPhone app is free to download, and you sign in with a Tresorit account. Its App Privacy label lists contact info, a user ID and usage data as linked to you, including for advertising or marketing.

Good for: files you need on several devices, including Windows or Android, or want to share safely. Limits: it’s a new account and a new place to keep track of. If you lose both your password and your recovery method, the provider can’t get your files back.

Option 4: Encrypt files before they reach any cloud

If you already pay for iCloud Drive, Dropbox, Google Drive or OneDrive, you can add encryption on top instead of moving everything.

Cryptomator creates an encrypted vault inside the cloud you already use. Its App Store page lists iCloud Drive, Dropbox, Google Drive, OneDrive, SharePoint, pCloud, Box, WebDAV and S3. Files are encrypted on your iPhone before they are uploaded. It’s open source, and its App Privacy label says no data is collected.

The free version opens your vaults read-only. To add or edit files you need the full version, an in-app purchase with a 30-day free trial.

Good for: keeping your current cloud while making its contents unreadable to the provider. Limits: one more password to remember, and the cloud provider can still see file sizes and when you sync.

Option 5: A vault app that keeps files on the iPhone

A vault app stores files inside its own encrypted space, behind a code that isn’t your iPhone passcode. That is the main reason to choose one: it protects against people who use your phone, not only against servers.

Cubbylock is a secure folder app in development. It is designed to encrypt every file on the iPhone, unlock with its own code plus optional Face ID, and offer an optional encrypted iCloud backup. See the planned features.

Good for: IDs, scans and private files you want out of reach of anyone who knows your passcode. Limits: files live on one phone unless the app backs them up. Check how backup and recovery work before you delete the originals.

What to check before you trust an app with your files

1. Where the encryption happens. Look for “encrypted on your device” or “end-to-end.” “Encrypted” alone can mean the company holds the keys.
2. Who holds the keys. If the company can reset your password and give your files back, it can also read them.
3. The unlock code. Does the app have its own code, or does it open with your iPhone passcode?
4. Backup and recovery. What happens if you lose your phone, delete the app or forget the code? Write down any recovery key.
5. The App Privacy label. On the App Store page, scroll to App Privacy. Developers fill it in themselves, so treat it as their claim, not a test result.
6. Price after the free tier. Note the storage limit and what the paid plan costs before you depend on it.

Popular secure file storage apps compared

From each app’s US App Store page and Apple’s support documentation, checked 1 Nov 2026. Prices change; check the listing before you pay.

App	Type	Encryption	Free tier	Paid plans	App Privacy label	Requires
iCloud Drive (Apple)	Cloud, built in	End-to-end with Advanced Data Protection; Apple holds keys without it	Part of your iCloud storage	iCloud+ storage plans	Built in	Built in
Proton Drive	Cloud	End-to-end	5 GB	From $4.99/month or $47.90/year	Diagnostics, not linked to you	iOS 16
Tresorit	Cloud	End-to-end, encrypted on device	Not stated on the listing	Sold through a Tresorit account	Contact info, user ID, usage data linked to you	iOS 15
Cryptomator	Encryption layer on your own cloud	Encrypted on device before upload	Read-only access to vaults	Full version $9.99 or $19.99 listed, 30-day trial	Data not collected	iOS 17

What this doesn’t protect

• Anyone who knows your iPhone passcode, for iCloud Drive and a locked Files app. Only an app with its own code, set to something different, avoids this.
• A lost password and a lost recovery key. With end-to-end encryption, neither Apple nor the app maker can open your files. That’s the point, and also the risk.
• Copies outside the app. The original in Downloads, Recently Deleted, an email attachment or a chat stays readable. Delete those after you move a file in.
• Files you share. Once someone downloads a file, its copy is out of your control. iCloud links shared with “anyone with the link” aren’t end-to-end encrypted.
• Metadata. Cloud providers can usually still see how much you store and when you sync, even if they can’t read the files.
• A compromised phone. If someone has your unlocked iPhone or malware on it, any app you open there shows its files.

How we checked this

We checked the iCloud steps against Apple’s own documentation (support.apple.com) on 1 Nov 2026, for iOS 26 and later. Every app detail comes from that app’s US App Store page on the same date, plus Cryptomator’s own documentation for its free version. We haven’t tested this guide on a device yet.

Methods compared

Method	Opens with your iPhone passcode	Separate code	Provider can read files	Cost
iCloud Drive, standard	Yes	No	Apple holds the keys	iCloud storage plan
iCloud Drive with Advanced Data Protection	Yes	No	No	iCloud storage plan
Proton Drive or Tresorit	Depends on the app lock you set	Optional app lock	No, end-to-end encrypted	Free tier or subscription
Cryptomator vault	No, needs the vault password	Yes	No, encrypted on device	Free read-only; paid to write
Cubbylock (in development)	Designed not to	Designed to use its own code	Designed so only you can read files	Free download planned

If you mainly worry about servers, turn on Advanced Data Protection or use an end-to-end encrypted cloud. If you worry about people who know your passcode, add something with its own code. For the full picture of what iOS can lock, read secure folder on iPhone.