ottercraft.dev

Guide · OtterDrop

Send files to someone on a different Wi-Fi

When your phone and your laptop are on the same network, OtterDrop puts them together with nothing to type. Getting a device that isn't on your network into the same room takes four characters.

Open OtterDrop →

Where the code is

Open drop.ottercraft.dev and look at the card at the top left. Under Room code there are four characters, next to a QR code. That is the room you are in. You always have one, even when you are alone in it, so there is nothing to create or start.

Below the code is the link for the same room, ending in #r= and those four characters. Copy puts it on your clipboard.

Three ways to get someone in

All three do the same thing, so use whichever suits the situation:

Why the codes look like that

The alphabet has no i, l or o in it. Those are the characters people mishear as 1 and 0, so they are simply not used. If you type one anyway, it gets read as the digit you probably meant, which means a code read out badly over a bad line usually still works.

Four characters is short enough to say once and have the other person get it right. It is also short enough that someone could try codes at random and land in a live room, so the room server counts attempts: ten different codes a minute from one network, after which it stops answering for a while. Retrying the same code as many times as you like is free, so a flaky connection reconnecting doesn't use up your allowance.

What happens when you join

You leave the room you were in and appear in the new one, and so does every device that was already connected to you. Transfers already running keep running: files move directly between devices, and that connection is separate from the one that introduces devices to each other.

The other person's device shows up in your list within a second or two, and from then on it behaves like any other device in the room. Drop a file on the page and they can take it. They can share back the same way.

Where this stops working

A code gets a device into your room. It cannot make two networks let those devices talk to each other, and that is a real limit rather than a bug.

Files in OtterDrop go straight from one device to the other. There is no relay server in the middle, on purpose: a relay would mean your files passing through a machine of ours, which is the one thing the whole tool exists to avoid. So when both ends are behind networks that block direct connections, the device shows up in the room but the transfer cannot start. Office, hotel and university networks are the usual culprits. Mobile data works more often than people expect. If both sides are stuck, one of you turning on a phone hotspot and putting the other on it is the reliable fix, though at that point you are both on one network and don't need a code at all.

A room holds up to eight devices.

Handing out a code

Anyone who has the four characters can join the room and see the names of the files being offered in it, so treat a code the way you would treat a meeting link. A room with nobody in it is released, and the code goes back into circulation about ten minutes later, so an old code you sent someone last week is unlikely to still point anywhere.

The code lives in the part of the link after the #. Browsers don't send that part to a web server when they fetch a page, so the code stays out of web logs on the way in. The room server does see it, because it has to know which room to put you in, but it stores nothing beyond which code a network is currently using, and it never sees a file.

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