Why I Built a File-Transfer Tool That Can't See Your Files

2026-07-15

In July 2025, WeTransfer updated its terms of service and quietly added a clause that let them use the files you upload to "improve, train and develop" machine-learning models. People noticed. The backlash was loud enough that within days the company walked the wording back and said it wasn't actually training AI on your transfers. But the damage was done — a lot of us had already read the same sentence and thought the same thing: wait, you had my files the whole time, and this is the arrangement you were considering?

Then in December they trimmed features and dropped the free tier to 3GB a month. I'm not writing this to dunk on WeTransfer — running that kind of service costs real money and I understand why the free lunch shrank. I'm writing it because the whole episode made an old, boring problem suddenly obvious to everyone at once.

The problem was never the terms — it was the model

Here's the thing people kept missing in the angry threads. The AI clause was bad, but it was a symptom. The real issue is the shape of the service: you hand your file to a company's server, the company holds it, and then you trust the company's promises about what it does with it. Change the promise — training clause today, "data partner" tomorrow, a breach next year — and your file is already sitting on someone else's disk. You gave up control at step one. Every "we won't look at your files" pledge is only as good as the current management and the current terms page.

I didn't want to write a better promise. I wanted to remove the step where the promise matters.

So the file just... doesn't go to a server

That's Share Files. When you use it, your file goes straight from your device to the other person's device. It doesn't pass through my server on the way, because there's nothing to pass through — I don't have a file server. I couldn't read your transfer if I wanted to, and I don't want the liability of being able to.

The technology under it is a browser feature called WebRTC. It's the same peer-to-peer plumbing that video calls use to send your camera feed directly to the other person instead of routing it through a middleman. Two browsers negotiate a direct connection and then talk to each other. Files ride over that same direct pipe.

There's one honest asterisk. To find each other, the two browsers need to swap a tiny bit of connection info first — "here's my address, here's how to reach me." That handshake, a few kilobytes of coordinates, goes through a small worker so the two devices can shake hands. Your actual file never does. It's the difference between a switchboard operator connecting your call and a stranger listening to it. Once the two browsers are connected, I'm out of the loop entirely.

No account. No email. No upload bar slowly filling while you wonder where the bytes are going. One device makes a 6-digit code (or a QR you can scan), the other joins, and the transfer happens between the two of you.

The honest limitations

I'd rather tell you where this breaks than have you find out at the worst moment.

Both devices have to be online at the same time. This is a live pipe between two browsers, not a mailbox. You can't "send" a file and have the other person grab it tomorrow — there's no server holding it in the meantime. If that's what you need, this is the wrong tool, and honestly WeTransfer or email is fine for that.

Really strict networks can block the direct connection. Some locked-down corporate and university firewalls refuse the kind of peer-to-peer connection WebRTC needs. When both people are behind that kind of network, the two browsers sometimes can't find a path to each other. The usual fix is dumb but effective: put both devices on the same Wi-Fi.

That's the trade. In exchange for those two constraints, your file never lands on anyone's server, there's no size cap I have to enforce because I'm not paying to store anything, and there's no terms-of-service page that can quietly change what happens to your data — because your data was never mine to begin with.

If your transfer is two people who are both around right now — phone to laptop, laptop to a friend across the table or across the world — try it. It's free, there's nothing to sign up for, and the best feature is the one you can't see: the part where I can't see your files.

— Milo 🐨