A signed contract. Tax documents. Photos of your passport. Design files for a client. Some files are too big for email, and some are too personal to leave sitting in an inbox or behind a shareable link. Here's how to send both kinds safely.
Why the usual ways aren't very private
- Email attachments are usually limited to around 25 MB. Copies stay in both mailboxes, often for years, and can be forwarded with one click.
- Cloud share links handle big files, but anyone who gets the link can usually open it, and links get forwarded. The file also stays online until someone remembers to delete it.
- Unless a service uses end-to-end encryption, the company storing your file can technically access it.
What "private" file sharing really means
Before you send something sensitive, check that the method does all four of these:
- Encrypts the file on your device, before it leaves.
- Lets only the recipient unlock it. Not the app company, not anyone in between.
- Has no public link that can be forwarded or guessed.
- Lets you choose exactly who gets it.
Quick comparison
| Email attachment | Cloud share link | GSTNet | |
|---|---|---|---|
| Encrypted on your device before sending | Usually no | Usually no | ✓ Yes |
| Only the recipient can open it | ✗ | Anyone with the link | ✓ Yes |
| No link to forward | Can be forwarded | ✗ | ✓ Yes |
| Large files | Small limit | ✓ | ✓ Sent in pieces |
How to send files with GSTNet
GSTNet works on iPhone, iPad and Windows, so you can send from your phone or straight from your PC.
- Add the recipient. Open Contacts, tap Add Contact and enter their GST-ID.
- Open your conversation with them.
- Attach the photo or file from inside the conversation and send it.
- That's it. The file is encrypted on your device, and only the recipient can decrypt it.
Large files are sent in pieces, so they can take a while on a slow connection. Use Wi-Fi for big files when you can.
To free up space later, go to Settings → Storage & Data → Clear Downloaded Files. This removes downloaded copies from your device only. It doesn't delete your messages or anyone else's copy.
Great for work
- Lawyers and consultants: contracts and confidential drafts
- Accountants: tax returns and financial statements
- Designers and photographers: large originals for clients
- HR and recruiting: ID documents and offer letters
- Real estate: signed agreements and ID copies
If your industry has specific rules for handling personal data, check that your process meets them. A secure app is one important part of that.
6 tips for sending sensitive files
- Double-check the GST-ID before sending. Sending to the wrong person is the most common mistake. Confirm the ID in person or by phone first.
- Don't also email it "just in case." A second copy in an inbox undoes the privacy you just gained.
- Name files clearly, like "2026 Tax Return – J. Smith.pdf", so nobody opens the wrong one.
- Use Wi-Fi for large files. It's faster and saves your mobile data.
- Clear downloaded files on shared or work devices when you're done.
- Lock your phone and computer with a passcode or password. Anyone who can unlock your device can see what's on it.
Questions
Can Global Space Technology see the files I send?
No. Files are encrypted on your device before they are sent, and only the recipient can decrypt them. We don't have the keys.
Can I send files from my Windows PC?
Yes. Encrypted file transfer works in the Windows app as well as on iPhone and iPad.
Does the recipient need GSTNet?
Yes. You both use GSTNet and add each other by GST-ID.
Is sending files free?
Every feature, including sending files, is free for the first 90 days. After that, sending files is part of Full Access, which is $79.99 per year. See the Pricing page.
What does Clear Downloaded Files do?
It removes downloaded copies of files from your device to free up space. It doesn't delete your messages or the other person's copy.
Send it. Only they can open it.
End-to-end encrypted file transfer on iPhone, iPad and Windows.